A unique squid-like 'belemnite' found in the NJ woods
This past winter I was in New Jersey and stopped by a creek where I found this. This is a part of a belemnite [Belemnitella americana], an extinct order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous (~214-80 mya); these are common to the NJ area and the NE USA (as well as all over the world).
The cone (rostrum) you are looking at was inside the animal and served as part of an internal skeleton-like structure; it also served as a counter-weight while moving in the water. On the cross-section (C & D), notice the radial symmetry which sprouts from a central axis outward, these are made of calcite crystals, deposited in concentric layers as the animal grew. The symmetry runs through the entire cylindrical body to the apex. These animals were very abundant in the sea and they had 10 arms that had hooks on them which they used to catch prey (soft body fossils exist). There is extensive literature on them available.
Image C is most interesting, because there is a bore hole on it, something quite commonly found on the exterior shells of clams, etc. I found that according to Seilacher (1969), micro barnacles would often bore holes in dead (and possibly live) belemnite rostrums on the horizontal plane just like this. See: Seilacher, A. (1969). Paleoecology of boring barnacles. Am. Zoologist, 9:705-719. Univ. of Tubingen, Germany.
Notice the uniform long shape, the sleekness of this evolutionary mini marvel.... as Dawkins has said, "Science is the poetry of life."
Hope you find this interesting.