Ancestors to ammonites, Orthoceras are extinct sea creatures dating from the lower Ordovician to Triassic ages (500 to 190 million years ago).
Their shells are straight rather than coiled and can range in size from a few inches to over six feet. Their shells fell to the floor of the ocean when they died, where the shells were covered in sediment. Here they eventually became stone and are preserved in black limestone.
1 1/2" – 2 1/2" long