Agelas dispar forms massive irregularly-shaped, sometimes bulbousmounds or may be encrusting. It can grow to as much as across. The consistency is spongy but firm; the surface is smooth with many exhalent pores of irregular shape and size, often in shallow pits. The colour externally is pinkish-brown, reddish-brown or deep brown. Internally there are large cavities, many primary canals across and narrow secondary canals. There is a fibrous, tightly-meshed skeleton made of spongin with ascending and tangential fibres. The spicules consist of bundles of acanthostyles.