ID please

[Pinner]

Just curious if anyone knows what this rippled brown stuff is. Thanks
http://img.photobucket.com/albums/v17/Pinner/100_0659.jpg

[marie]

Some sort of sponge, maybe

[Johnny Reefer]

Some sort of sponge, maybe
That's what I thought when I first saw the pic. I say sponge too. Possibly a type of demosponge (spicules consisting of silicon dioxide or silica).

[danny zubot]

Is it hard though? It looks like it could be some sort of encrusting coral.