A crinoid slab is a fossil-rich rock surface covered with the remains of crinoids, marine animals related to sea stars and sea urchins. Crinoids, often called "sea lilies" because of their flower-like appearance, lived attached to the sea floor by long, stalk-like structures.

These animals thrived in ancient oceans, particularly during the Paleozoic era, around 300 to 500 million years ago. A crinoid slab typically showcases fossilized segments of their stalks, calyxes (body), and delicate arms.

These slabs provide a window into ancient marine environments and are prized for their intricate, often beautiful fossil patterns.

Origin: Germany