Endermite

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

Appearance
Endermites have a similar appearance to silverfish, except they are purple, emit the "portal" particles like other end-related items and mobs, and do not have the thin "frills" around them that silverfish have. Endermites will get a new model in a later snapshot.

Behavior
Endermites do not currently spawn naturally in any biome or dimension. Instead they occasionally appear in the place of an Enderman that teleports, or when the player throws an Ender Pearl. Each individual Enderman can only spawn a limited number of Endermites; every time it teleports, the chance of producing one is 15%, minus 1% for each Endermite it has already spawned. Ender Pearls have a 5% chance of spawning an Endermite when used. Endermites are not harmed directly by water like Endermen are, but can drown if they stay submerged for too long. However, if there are a lot of Endermen around, then the Endermen will see the Endermite, move towards it, get soaked by water, and teleport away possibly leaving the next generation of mites to cause the same thing. 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 mob sorting systems and 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, unless killed.

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.