Sea Lily

Delocrinus missouriensis is Missouri's official state fossil, designated in 1989. Despite the name, sea lilies are animals — echinoderms related to starfish and sea urchins — not plants. Delocrinus was a stalked crinoid that anchored itself to the seafloor and extended feathery arms into the water to catch food. During the Pennsylvanian period, Missouri lay beneath a warm, shallow inland sea, and crinoids were among its most abundant animals.

Delocrinus missouriensis had three main parts: a root-like holdfast that anchored it to the seafloor, a segmented stem made of stacked disc-shaped plates called columnals, and a small cup (calyx) at the top bearing flexible arms. The arms were lined with tiny tube feet that swept plankton and organic particles toward the mouth at the center of the calyx.

Sea lilies were passive filter feeders. They did not move in search of prey but relied on ocean currents to deliver food. Crinoids as a group survive today in deep ocean waters, but Delocrinus missouriensis died out at the end of the Pennsylvanian period as the inland sea retreated from Missouri.

Missouri designated Delocrinus missouriensis as its state fossil in 1989. The species was named directly for the state, making it a natural fit for the designation. Crinoid stem segments — small disc-shaped columnals with a hole in the center — are among the most common fossils in Missouri's Pennsylvanian limestone outcrops, familiar to anyone who has walked a gravel road or creek bed in the central part of the state.

The choice highlighted Missouri's deep marine past. Roughly 300 million years ago the state was not landlocked but submerged under a warm tropical sea, and the dense crinoid gardens on its floor left behind some of the thickest fossil-bearing limestone beds in the Midwest.

Crinoid fossils from the Pennsylvanian period are found across a broad belt of central and western Missouri wherever limestone bedrock is exposed — in road cuts, creek banks, and quarry walls. The Kansas City area and the counties along the Missouri River corridor have particularly rich exposures of Pennsylvanian strata.

Columnal stem segments are so abundant in Missouri that they erode freely into creek gravel and road fill across the region. Complete calyces with preserved arms are rarer and show up mainly in undisturbed limestone beds. The University of Missouri Department of Geological Sciences in Columbia holds reference collections of Missouri crinoid material.