The fossil was found at a cliff in Denmark. Fossilized vomit is called regurgitalite, and it's a type of trace fossil, which ...

“But here’s an animal, probably a type of fish, that 66 million years ... prey in the Cretaceous-era sea. The fossil is expected to go on display in a small exhibit at Denmark’s Geomuseum ...

The fossil also appears to contain bryozoans, Olsen says, very tiny creatures that are also called moss animals, but it's unclear if they were part of the fish's attempted meal in this case.