the orange sea lily is a stalkless crinoid. it has twenty to thirty five arms long radiating from the calyx, a cup-like body with a lid, the tegmen. each arm is feather-like and has many pinnules projecting alternately from one side and the other. these have an ambulacral groove on the oral surface which is continuous with the groove on the arm. the arms are usually orange with yellow curved up tips but there is some variation in colour and they are sometimes white with black tips. the grooves are black. the arms and pinnules are composed of a series of jointed plates and there are three tube feet at each junction. the tube feet produce strands of mucus which trap plankton. food particles are passed along the grooves by cilia to the mouth which is at the centre of the tegmen.