I sent this image to Bill Rudman at the Sea Slug Forum because we were unable to identify it. Here is his response:
One interesting feature in your photo is that scattered over the reddish sponge are whitish blobs which each have a pair of small black spots in them. I have ringed one of them. There are almost certainly small animals called kamptozoans or entoprocts whhich we now know are the food of species of Trapania. These kamptozoans are often found living on certain sponges, which is why the Trapania are often found on such sponges.