This is a very large sea biscuit with a strong inflated test, growing to a maximum length of around 200 mm (8 in).

The oral (under) surface is fairly flat, with a deep depression around the mouth, and with deeply indented food grooves.

During the daytime it is inactive and buries itself or covers its test with fragments of shell and pieces of seagrass, holding these in place with its tube feet.

[2][3] In Panama, breeding takes place annually in the rainy season, with spawn being liberated into the sea.

The eggs contain much yolk to sustain the developing larvae, which settle on the seabed and undergo metamorphosis after about six days.