These are torn sponge fragments. Myxilla incrustans is yellow and Mycale adhaerens is purple. Note the more stringy appearance of the Mycale. Scale is millimeters. Photo by Dave Cowles, July 2005.
Mycale adhaerens is not limited to growing on scallops. The sponge shown below is often found growing in Padilla Bay near March Point June 2006. It is tan with yellowish parts when fresh and quickly fades to all tan after being collected. According to the spicules and growth form this is also Mycale adhaerens.
Mycale adhaerens sponges of different hues on Chlamys hastata scallops. The scallop on the right also has a Myxilla incrustans sponge growing on the lower valve (not visible). Collected at 15 m depth, Coffin Rocks. (Photo by: Dave Cowles, July 2005)
