A sharp lipped boot sponge (Rhabdocalyptus dawsoni) shelters an inquisitive grunt sculpin on a deep vertical wall. These sponges can grow very large with some specimens reaching 5 feet (1.5 m) in length. This sponge was found close to 100 feet (30.4 m) of depth, but others have been discovered as deep as 1650 feet (502.9 m). The outside of the sponge is always covered in silt from the water filtration that takes place. The sharp lipped boot sponge has a range from Alaska to southern California.