Crinoid plate fossil from Morocco. Crinoids, also known as sea lilies,are members of the Echinodermata phylum along with starfish and sea urchins. They resemble graceful underwater flowers and have parts that look like roots anchoring them to the ocean floor. They are amongst the oldest fossils in the world dating back to the Ordovician period, 450 million years ago. The stand is not included in the price.