Fossils of the Fezouata formation , which are usually squashed flat ( although some do retain some degree of their original three-dimensionality ) are often coated with a dusting of pyrite , and tin ??
Fossils of the Fezouata formation , which are usually squashed flat ( although some do retain some degree of their original three-dimensionality ) are often coated with a dusting of pyrite , and tin ; this aspect of the fossil preservation is very similar to that at Chengjiang .