Endermite

An Endermite is the second smallest mob in Minecraft.

Spawning
Any ender pearl used has a 5% chance of spawning an endermite.

Drops
Endermites have no drops.

Behavior
Endermites can drown if submerged in water for too long.

Endermites despawn within 2 minutes, regardless of the player's distance from the endermite, unless they are named with a name tag. If they are named, they will never despawn and last until they are killed.

Endermites will take damage if walking on soul sand, due to it sharing its short hitbox with silverfish.

Trivia

 * Dinnerbone has stated he has an "Ultimate Plan" with Endermites that might include the dragon egg. However, he also mentioned he hasn't discussed this idea with the rest of the team yet.