Chonetes

Chonetes, genus of extinct brachiopods, or lamp shells, found as fossils in marine rocks of Silurian to Permian age (about 444 million to 299 million years old). Chonetes and closely related forms were the longest lived group of the productid brachiopods. The shell is small, one half concave in form and the other moderately convex. The horizontal margin of the shell bears short, angled spines that the animal used in anchoring or attaching itself. The internal structure of the shell of Chonetes is distinctive.