Bowerbank's Halichondria is easy to confuse with the breadcrumb sponge. Older specimen have long thin, stringy branches which emerge from a thin crust. Young specimen lack these stringy branches. Since the Delta Works were built, Bowerbank's Halichondria is found more often than the breadcrumb sponge. It used to be the other way around. But this sponge is more resistant to mud. Bowerbank's Halichondria is also known as crumb-of-bread sponge or the common sponge.