hitchhiker id.. good close up photo

[rc cola]

Hey I was wondering if anyone could tell me what this is... i am guessing it is some sort of sponge. it is about 1/2 the size of a penny. Please correct me if i am wrong.
Thanks!

 

[rc cola]

bump

 

[perfectdark]

Gelloides fibulatus AKA Thorny Horney Sponge... IMO

 

[rc cola]

Is this rare? I did a search and saw something that said " Has two forms, encrusting and tubular. Not sustainable and rarely seen in the trade"
thanks!

 

[perfectdark]

Good question I dont know, I dont have a lot of knowledge on sponges. If ReefKprZ sees this thread maybe he knows, I think I remember him saying hes into sponges too. Or you can PM him and point him to this post.