Receptaculites oweni
Middle Ordovician
Kimmswick Formation
Pike County
Missouri

Big 200mm receptaculite showing the classic spiral pattern

Receptaculites oweni is a bizarre and beautiful fossil from the Ordovician to Devonian periods, often nicknamed the “sunflower coral” for its distinctive spiral, radiating pattern. Though its exact classification has long puzzled paleontologists, it’s most likely related to early algae. With its geometric, golden-ratio-like structure, R. oweni stood anchored to the seafloor, absorbing nutrients in ancient shallow seas. Its fossils are striking and mysterious—a perfect blend of science and natural art from over 400 million years ago.