this is a sponge, isn't it? (pic)

[Wormy]

Looks more like a very attractive tunicate (sea squirt). Sounds like he behaves like one too. Hope he does well.

 

[kennerd]

Ditto on the sea squirt.

I have one that is about 3.5" across that I got as a bonus hitchhiker on a sun polyp colony. Didn't know he was there until I went to put the coral in the tank after acclimating it, and was promptly squirted in the face!!

Mine is a pretty ugly color compared to yours. Mine looks like someone took a half dozen caramels, half chewed them & stuck it on the rock.. When you shine a flash light through it, you can barely make out the internal organs, etc.

The mouths, or vents, have orange, blue, green, grey stripes that I'm sure will look far better when I get some actinics over the tank.

Good luck.

 

[Jrsydevi1]

This little guy came in with my
gulf rock.. he has shown a bit of growth in the month or so that he's been here..
He was basically rectangular at first, but seems to be growing "horns".

He is very small, about 1/2 inch or less, and i assume it's a sponge, but it shrinks a bit during lights out, and the hole that appears at the tip of the "horn" seems to close up.. I didn't know sponges did that..

Thanks