Sponge ID

Images: 

I saw these purplish-black sponges all over Little Cayman about a month ago, but never found out what they are.  They are about the size of a vase sponge, maybe a little larger.  I apologize for the photo quality; this photo is actually part of the background in a fish photo.

 

Thanks!

Allison

Design by Joanne Kidd, development by Ben Weintraub