Tidepool Tim says,  “Warty sponge populations seem to ebb and flow every few years.  I have always been able to find specimens in kelp beds and in rocky seaweed plains that drain dry at low water but that have a good overtstory of seaweeds to keep the sponge wet at low tide.  This sponge has a real angular makeup and fractures into pieces easily. Bloodstars seem to graze on the sponge. The bright yellow color makes it easy to spot and a nice addition to any coldwater aquarium.”