Any ideas? This is from a Silurian period hillside in the Rose Hill-Keefer formation in Western Maryland. This piece of rock is about 2 ft long and 1ft across. I thought maybe this could be a coral fossil or some kind of Bryozoa, but neither seems certain. Another possibility that came up was that it might be a ripple fossil, but others have suggested that this is probably too small for that. Any opinions? Thanks.