what the heck is on this hammer?

[jonesdeini]

Hello everyone,

This hammer always looks great, good polyp extension and I've seen continuous growth since I got it. I was cleaning the side of my tank and noticed this.

It resembles a pineapple sponge, but it's much larger and yellowish in color.

http://imgur.com/a/6urCU

 

[greech]

Tough to see in the pics but it just looks like a yellow sponge. Not uncommon for sponge to grown on coral skeletons.