This is one of the nicest splits I've seen lately. The colors are rich and vibrant and chambers are large, well defined and full of quartz and calcite. This is one fossil, split in half and polished to reveal the hidden living chambers that once housed a predatory mullusk. These are getting much harder to find and especially as nice of quality as this one showcases. Ammonites were predators that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus.