floor, and fed mainly by filtering tiny edible
particles of food from the general ooze on
the ocean floor. Its protective, convex
(domed) shield-like carapace was about the
size of a fingernail and it covered the softer,
vulnerable parts beneath, so that only the
ends of the limbs, two antennae-like feelers,
which were directed forwards, and the long
rail spine were visible from above