Crinoids are marine animals that are related to sea urchins. The word comes from the Greek for lily, as their arms reminded the Greeks of the petals of lilies. They live on the sea bed, some with arms that rise directly from the main body, others rising on stalks from a rocky holdfast.

If they have a stalk they are called sea lilies. If they have no stalks they are called feather stars.

Crinoids have their mouths at the base of their feeding arms. The feeding arms wave in a rhythmic way so as to carry food down the arms to the mouth. Those without stalks can become free-swimming as adults.

Crinoids have lived for hundreds of millions of years and are important fossils in limestones. The video shows that.