what the heck is this thing

actually have now found two of them

 

not sure but it looks cool. About how big is it?

 

pretty cool, i never seen it before but i will take a wild guess and say it might be some kind of sponge or worm??

Someone here will probably know.

 

both of them when fully extended are about 1 1/2"

i thought some kind of nudibranch but cant find any pics that match up

 

That's a nudibranch. I've seen pics before of that exact same type, too. But I can't remember where

 

Definitely a nudibranch.Most of the hitchhiking nudibranches are some kind of coral predator.....be weary.