diff --git a/src/pocketmine/Server.php b/src/pocketmine/Server.php
index 4d299333a..4a52bb250 100644
--- a/src/pocketmine/Server.php
+++ b/src/pocketmine/Server.php
@@ -39,6 +39,7 @@ use pocketmine\entity\Human;
 use pocketmine\entity\Item as DroppedItem;
 use pocketmine\entity\PrimedTNT;
 use pocketmine\entity\Snowball;
+use pocketmine\entity\Squid;
 use pocketmine\entity\Villager;
 use pocketmine\entity\Zombie;
 use pocketmine\event\HandlerList;
@@ -2415,6 +2416,7 @@ class Server{
 		Entity::registerEntity(Snowball::class);
 		Entity::registerEntity(Villager::class);
 		Entity::registerEntity(Zombie::class);
+		Entity::registerEntity(Squid::class);
 
 		Entity::registerEntity(Human::class, true);
 	}
diff --git a/src/pocketmine/block/Block.php b/src/pocketmine/block/Block.php
index 0b808250b..7b371ddd0 100644
--- a/src/pocketmine/block/Block.php
+++ b/src/pocketmine/block/Block.php
@@ -25,6 +25,7 @@
 namespace pocketmine\block;
 
 use pocketmine\entity\Entity;
+use pocketmine\entity\Squid;
 use pocketmine\entity\Villager;
 use pocketmine\entity\Zombie;
 use pocketmine\item\Item;
@@ -494,7 +495,7 @@ class Block extends Position implements Metadatable{
 		//TODO: Slime
 		[Item::SPAWN_EGG, Zombie::NETWORK_ID],
 		//TODO: PigZombie
-		//TODO: Replace with Entity constants
+		[Item::SPAWN_EGG, Squid::NETWORK_ID],
 
 
 		//Seeds
diff --git a/src/pocketmine/entity/Ageable.php b/src/pocketmine/entity/Ageable.php
index 871c8efec..7067af087 100644
--- a/src/pocketmine/entity/Ageable.php
+++ b/src/pocketmine/entity/Ageable.php
@@ -23,5 +23,9 @@ namespace pocketmine\entity;
 
 
 interface Ageable{
+	const DATA_AGEABLE_FLAGS = 14;
 
+	const DATA_FLAG_BABY = 0;
+
+	public function isBaby();
 }
\ No newline at end of file
diff --git a/src/pocketmine/entity/Animal.php b/src/pocketmine/entity/Animal.php
index 7803e2140..18bff79dc 100644
--- a/src/pocketmine/entity/Animal.php
+++ b/src/pocketmine/entity/Animal.php
@@ -24,4 +24,14 @@ namespace pocketmine\entity;
 
 abstract class Animal extends Creature implements Ageable{
 
+	public function initEntity(){
+		parent::initEntity();
+		if($this->getDataProperty(self::DATA_AGEABLE_FLAGS) === null){
+			$this->setDataProperty(self::DATA_AGEABLE_FLAGS, self::DATA_TYPE_BYTE, 0);
+		}
+	}
+
+	public function isBaby(){
+		return $this->getDataFlag(self::DATA_AGEABLE_FLAGS, self::DATA_FLAG_BABY);
+	}
 }
\ No newline at end of file
diff --git a/src/pocketmine/entity/Entity.php b/src/pocketmine/entity/Entity.php
index 00a3c7967..81f45e37d 100644
--- a/src/pocketmine/entity/Entity.php
+++ b/src/pocketmine/entity/Entity.php
@@ -196,12 +196,35 @@ abstract class Entity extends Location implements Metadatable{
 	/** @var \pocketmine\event\TimingsHandler */
 	protected $timings;
 
+	protected $MASK = 0;
+
 
 	public function __construct(FullChunk $chunk, Compound $nbt){
 		if($chunk === null or $chunk->getProvider() === null){
 			throw new ChunkException("Invalid garbage Chunk given to Entity");
 		}
 
+		$PF = 0x200;
+		if($this instanceof Living){
+			$this->MASK |= 0x100 | $PF;
+		}
+		if($this instanceof Ageable){
+			$this->MASK |= 0x400;
+		}
+		if($this instanceof Monster){
+			$this->MASK |= 0x800;
+		}
+		if($this instanceof Animal){
+			$this->MASK |= 0x1000;
+		}
+		if($this instanceof WaterAnimal){
+			$this->MASK |= 0x2000;
+		}
+		if($this instanceof Tameable){
+			$this->MASK |= 0x4000;
+		}
+		//AMBIENT = 0x100 | 0x8000;
+
 		$this->timings = Timings::getEntityTimings($this);
 
 		if($this->eyeHeight === null){
diff --git a/src/pocketmine/entity/Living.php b/src/pocketmine/entity/Living.php
index 37cb3b8a4..de45d18e4 100644
--- a/src/pocketmine/entity/Living.php
+++ b/src/pocketmine/entity/Living.php
@@ -167,17 +167,33 @@ abstract class Living extends Entity implements Damageable{
 		}
 
 		if($this->dead !== true and !$this->hasEffect(Effect::WATER_BREATHING) and $this->isInsideOfWater()){
-			$hasUpdate = true;
-			$airTicks = $this->getDataProperty(self::DATA_AIR) - $tickDiff;
-			if($airTicks <= -20){
-				$airTicks = 0;
+			if($this instanceof WaterAnimal){
+				$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
+			}else{
+				$hasUpdate = true;
+				$airTicks = $this->getDataProperty(self::DATA_AIR) - $tickDiff;
+				if($airTicks <= -20){
+					$airTicks = 0;
 
-				$ev = new EntityDamageEvent($this, EntityDamageEvent::CAUSE_DROWNING, 2);
-				$this->attack($ev->getFinalDamage(), $ev);
+					$ev = new EntityDamageEvent($this, EntityDamageEvent::CAUSE_DROWNING, 2);
+					$this->attack($ev->getFinalDamage(), $ev);
+				}
+				$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, $airTicks);
 			}
-			$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, $airTicks);
 		}else{
-			$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
+			if($this instanceof WaterAnimal){
+				$hasUpdate = true;
+				$airTicks = $this->getDataProperty(self::DATA_AIR) - $tickDiff;
+				if($airTicks <= -20){
+					$airTicks = 0;
+
+					$ev = new EntityDamageEvent($this, EntityDamageEvent::CAUSE_SUFFOCATION, 2);
+					$this->attack($ev->getFinalDamage(), $ev);
+				}
+				$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, $airTicks);
+			}else{
+				$this->setDataProperty(self::DATA_AIR, self::DATA_TYPE_SHORT, 300);
+			}
 		}
 
 		if($this->attackTime > 0){
diff --git a/src/pocketmine/entity/Squid.php b/src/pocketmine/entity/Squid.php
new file mode 100644
index 000000000..6f8509323
--- /dev/null
+++ b/src/pocketmine/entity/Squid.php
@@ -0,0 +1,167 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____  
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \ 
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/ 
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_| 
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ * 
+ *
+*/
+
+namespace pocketmine\entity;
+
+
+use pocketmine\event\entity\EntityDamageByEntityEvent;
+use pocketmine\event\entity\EntityDamageEvent;
+use pocketmine\item\Item as ItemItem;
+use pocketmine\math\Vector3;
+use pocketmine\network\protocol\AddEntityPacket;
+use pocketmine\network\protocol\EntityEventPacket;
+use pocketmine\Player;
+use pocketmine\Server;
+
+class Squid extends WaterAnimal implements Ageable{
+	const NETWORK_ID = 17;
+
+	public $width = 0.95;
+	public $length = 0.95;
+	public $height = 0.95;
+
+	/** @var Vector3 */
+	public $swimDirection = null;
+	public $swimSpeed = 0.1;
+
+	public function initEntity(){
+		$this->setMaxHealth(5);
+		parent::initEntity();
+	}
+
+	public function getName(){
+		return "Squid";
+	}
+
+	public function attack($damage, EntityDamageEvent $source){
+		parent::attack($damage, $source);
+		if($source->isCancelled()){
+			return;
+		}
+
+		if($source instanceof EntityDamageByEntityEvent){
+			$this->swimSpeed = mt_rand(150, 350) / 2000;
+			$e = $source->getDamager();
+			$this->swimDirection = (new Vector3($this->x - $e->x, $this->y - $e->y, $this->z - $e->z))->normalize();
+
+			$pk = new EntityEventPacket();
+			$pk->eid = $this->getId();
+			$pk->event = 15;
+			Server::broadcastPacket($this->hasSpawned, $pk);
+		}
+	}
+
+	private function generateRandomDirection(){
+		return new Vector3(mt_rand(-1000, 1000) / 1000, mt_rand(-500, 500) / 1000, mt_rand(-1000, 1000) / 1000);
+	}
+
+
+	public function onUpdate($currentTick){
+		if($this->closed !== false){
+			return false;
+		}
+
+		if($currentTick % 20 === 0 and mt_rand(0, 100) < 5){
+			$this->swimDirection = null;
+		}
+
+		$this->lastUpdate = $currentTick;
+
+		$this->timings->startTiming();
+
+		$hasUpdate = parent::onUpdate($currentTick);
+
+		if(!$this->dead){
+
+			if($this->y > 62 and $this->swimDirection !== null){
+				$this->swimDirection->y = -0.5;
+			}
+
+			$inWater = $this->isInsideOfWater();
+			if(!$inWater){
+				$this->motionY -= $this->gravity;
+				$this->swimDirection = null;
+			}elseif($this->swimDirection !== null){
+				if($this->motionX ** 2 + $this->motionY ** 2 + $this->motionZ ** 2 <= $this->swimDirection->lengthSquared()){
+					$this->motionX = $this->swimDirection->x * $this->swimSpeed;
+					$this->motionY = $this->swimDirection->y * $this->swimSpeed;
+					$this->motionZ = $this->swimDirection->z * $this->swimSpeed;
+				}
+			}else{
+				$this->swimDirection = $this->generateRandomDirection();
+				$this->swimSpeed = mt_rand(50, 100) / 2000;
+			}
+
+			$expectedPos = new Vector3($this->x + $this->motionX, $this->y + $this->motionY, $this->z + $this->motionZ);
+
+			$this->move($this->motionX, $this->motionY, $this->motionZ);
+
+			if($expectedPos->distanceSquared($this) > 0){
+				$this->swimDirection = $this->generateRandomDirection();
+				$this->swimSpeed = mt_rand(50, 100) / 2000;
+			}
+
+			$friction = 1 - $this->drag;
+
+			$this->motionX *= $friction;
+			$this->motionY *= 1 - $this->drag;
+			$this->motionZ *= $friction;
+
+			$f = sqrt(($this->motionX ** 2) + ($this->motionZ ** 2));
+			$this->yaw = (-atan2($this->motionX, $this->motionZ) * 180 / M_PI);
+			$this->pitch = (-atan2($f, $this->motionY) * 180 / M_PI);
+
+			if($this->onGround){
+				$this->motionY *= -0.5;
+			}
+
+		}
+
+		$this->timings->stopTiming();
+
+		return $hasUpdate or !$this->onGround or $this->motionX != 0 or $this->motionY != 0 or $this->motionZ != 0;
+	}
+
+
+	public function spawnTo(Player $player){
+		$pk = new AddEntityPacket();
+		$pk->eid = $this->getId();
+		$pk->type = Squid::NETWORK_ID | $this->MASK;
+		$pk->x = $this->x;
+		$pk->y = $this->y;
+		$pk->z = $this->z;
+		$pk->speedX = $this->motionX;
+		$pk->speedY = $this->motionY;
+		$pk->speedZ = $this->motionZ;
+		$pk->yaw = $this->yaw;
+		$pk->pitch = $this->pitch;
+		$pk->metadata = $this->dataProperties;
+		$player->dataPacket($pk);
+
+		parent::spawnTo($player);
+	}
+
+	public function getDrops(){
+		return [
+			ItemItem::get(ItemItem::DYE, 0, mt_rand(1, 3))
+		];
+	}
+}
diff --git a/src/pocketmine/entity/Villager.php b/src/pocketmine/entity/Villager.php
index 356174e7b..349575cf8 100644
--- a/src/pocketmine/entity/Villager.php
+++ b/src/pocketmine/entity/Villager.php
@@ -54,7 +54,7 @@ class Villager extends Creature implements NPC, Ageable{
 	public function spawnTo(Player $player){
 		$pk = new AddEntityPacket();
 		$pk->eid = $this->getId();
-		$pk->type = Villager::NETWORK_ID;
+		$pk->type = Villager::NETWORK_ID | $this->MASK;
 		$pk->x = $this->x;
 		$pk->y = $this->y;
 		$pk->z = $this->z;
@@ -81,4 +81,8 @@ class Villager extends Creature implements NPC, Ageable{
 	public function getProfession(){
 		return $this->namedtag["Profession"];
 	}
+
+	public function isBaby(){
+		return $this->getDataFlag(self::DATA_AGEABLE_FLAGS, self::DATA_FLAG_BABY);
+	}
 }
diff --git a/src/pocketmine/entity/WaterAnimal.php b/src/pocketmine/entity/WaterAnimal.php
new file mode 100644
index 000000000..cfb2b033a
--- /dev/null
+++ b/src/pocketmine/entity/WaterAnimal.php
@@ -0,0 +1,35 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____  
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \ 
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/ 
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_| 
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ * 
+ *
+*/
+
+namespace pocketmine\entity;
+
+abstract class WaterAnimal extends Creature implements Ageable{
+	public function initEntity(){
+		parent::initEntity();
+		if($this->getDataProperty(self::DATA_AGEABLE_FLAGS) === null){
+			$this->setDataProperty(self::DATA_AGEABLE_FLAGS, self::DATA_TYPE_BYTE, 0);
+		}
+	}
+
+	public function isBaby(){
+		return $this->getDataFlag(self::DATA_AGEABLE_FLAGS, self::DATA_FLAG_BABY);
+	}
+}
diff --git a/src/pocketmine/entity/Zombie.php b/src/pocketmine/entity/Zombie.php
index a84d759d5..a828917e6 100644
--- a/src/pocketmine/entity/Zombie.php
+++ b/src/pocketmine/entity/Zombie.php
@@ -41,7 +41,7 @@ class Zombie extends Monster{
 	public function spawnTo(Player $player){
 		$pk = new AddEntityPacket();
 		$pk->eid = $this->getId();
-		$pk->type = Zombie::NETWORK_ID;
+		$pk->type = Zombie::NETWORK_ID | $this->MASK;
 		$pk->x = $this->x;
 		$pk->y = $this->y;
 		$pk->z = $this->z;