PLATYCERAS niagarensis is a gastropod, a snail. The Platyceras has a distinctive, curved shape. Shell is high and broad to the front. The posterior portion of the shell, at the apex, is usually slightly coiled in an asymmetrical fashion. Frequently, the front portions of the shells are broken, though the posterior sections are relatively well preserved. The Platyceras has a symbiotic relationship with crinoids. Sometimes they are found attached to the anal tube of the crinoid feeding off the waste products the crinoid produces. They are best known from Silurian and Devonian deposits around the world.
This Platyceras is .79 inches long and .43 inches wide. It sits on the side of a cream colored matrix from the bryozoan layer. On top of the matrix is a very well preserved brachiopod. The matrix is 2 3/4 inches long and 2 inches wide.
The Rochester shale has produced some spectacular fossils. The shale is a fine grained shale that preserves fossils in an exceptional manner.