Looks like a enderdragon....but smaller. It is not hostile nor is it large enough to fly.
how 2 tame
You tame it by feeding it warp bones. once you do that it will stare at you, blankly. if you then feed it a ender flesh then it will have blue eyes instead of purple (or red if you atack it). Once that happens you give your dragon a name. This is so on a multi-player server other players dont mix them up.
The baby ender dragon is fed warp dragon meat from end traders or a recipie. Then feed it to your dragon and it will be happy entering love mode (only mates in teir 6.) once you feed it 5 times it goes into the next teir:
teir 1:follows you...ummm doesn't do much.
teir 2: killz enemies...like a wolf. 30 HP and 5 damage.
teir 3: more damage (10)
teir 4: MOAR damage (15)
teir 5: purple fire ballzz! (One per 3 seconds and deals 20 damage)
teir 6: can mate
teir 7: can fly!
teir 8: MOAR DAMAGE!!! (25)
teir 9: more purple fire ballz (3)
teir 10: MORE DAMAGE FIREBALLS AND CAN CARRY YOU!!! (35, and 5)
what they do
they act like wolves. Except lead by a ender nest keeper.