Endermite

The Endermite is a mob that occasionally spawns when an Enderman is attacked or teleports away, or when the player teleports using an Ender Pearl.

Appearance
Endermites have a similar appearance to silverfish, except they are purple, emit purple "ender" particles like other end-related stuff, and do not have the thin "frills" around them that silverfish have.

Behavior
Endermites do not currently spawn naturally in any biome or dimension. Instead they occasionally appear in the place of an Enderman that was killed or teleported away, or when the player throws an Ender Pearl. Endermites are not harmed by water like endermen are, but can drown if they stay submerged for too long. Unlike silverfish, Endermites cannot enter blocks. However, they make the same sounds as silverfish.

Endermites are hostile towards the player. In normal difficulty, endermites do 1 heart of damage per hit, as opposed to 1/2 heart for a silverfish. Also, endermen are hostile towards endermites and will easily kill them, allowing for more possibilities in mob sorting systems and more resource friendly enderman farms.

Unlike other mobs, Endermites despawn within 2 minutes, unless they are named with a name tag. If they are named, they will last forever.

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.