Halichondria bowerbanki is a species of sponge that lives on rocky surfaces in the shallow subtidal, with occasional intertidal specimens under overhanging rocks. The physical appearance and structure of the species is variable and it has tassel-like irregular branches. Colonies can be up to 25 centimeters high with branches reaching 12 centimeters high. The color of the species is beige to brown in the summer, and light grey/yellow in the winter.