To be particular, this is a Canadoceras newberryanum, and was collected on Sucia island in Washington state.
Ammonites first appeared about 400 million years ago and were once so plentiful globally that particular species can be used to date rock strata (i.e., they are index fossils) — this one dates to between 70.6 and 84.9 million years ago. But Ammonites had their good years and bad like all species, and the last of them died out with the dinosaurs about 65 million years ago at the end of the Cretaceous.
While Ammonites look very similar to modern-day Nautilus shells, they’re actually only distant relatives. Of modern-day fauna, Ammonites are most closely related to squid and octopi.