Zombie taxon

In paleontology, a zombie taxon[1][2] (plural zombie taxa) or the zombie effect refers to a fossil that was washed out of sediments and re-deposited in rocks and/or sediments millions of years younger.

[3] That basic mistake in the interpretation of the age of the fossil leads to its title,[4] in that the discovered fossil was at some point mobile (or "walking") despite the original organism having been long dead.

When that occurs, the fossil is described as a "reworked fossil".

Jurassic ammonite internal mold redeposited (and bored ) in a Cretaceous sediment, thus a zombie taxon or remanié; Faringdon Sponge Gravel , England .