Tidepool Tim says,  “Crumb of bread is the most common sponge one will see in the tidepools around Cobscook bay in eastern Maine where I do my collecting.  It can be found as a mat or layer on the undersides of large stones. Other times it comes ashore having grown into the crevices amidst laminaria kelp holdfasts and other times it is just a thick carpet on the sea floor where blood stars, sea urchins, Irish moss, rock gunnels and other specimens are all in close proximity.  The larger holes or oscula are irregular across the surface and usually project up from the sponge perhaps 1/4" to 1/2" projections. Sometimes this sponge has a type of algae that grows inside its spicules - this will make the otherwise yellow sponge kind of green. Crumb sponge adds great color and nice structure in a coldwater aquarium.  It seems to survive quite well for months or even years in good clean sea water. Given its name - it really does look like a big gob of wet bread - even breaks off in clumps!”