Shark Coprolite

Sharks have two types of cloacal valves: scroll valve or spiral valve. Such valves increase the contact between the shark gut and food items, thus improving efficiency of nutrient uptake.

Scroll valves are found in advanced sharks such as carchariniforms, while spiral valves are found in more primitive groups like lamniforms.

A scroll valve produces a tightly-rolled "crepe" form of dropping (NPI). A spiral valve produces a corkscrew form of fecal pellet.