The valves are perforated by hexagonal areolae (pores) forming a radiating pattern of straight rows.

The margin of each valve has four to eight processes and a small, knob-like outgrowth called a pseudonodulus.

It is also found in the north west Atlantic Ocean, in the Gulf of Maine and the Bay of Fundy.

It has been found in Narmada river at the distance of 50 km from gulf of Khambat, Gujarat, India.

The form Actinocyclus normanii f. subsalsus is considered an invading species in the Great Lakes where it was probably introduced in about 1938 in ballast water.