3/3 found these on shore of Lake Diefenbaker in Saskatchewan, Canada. looked to be eroded from sandy deposits with layers of harder iron-rich rusty strata. the fossils themselves are heavy, mineralized with iron and then rusted? corals? all the same type or different? i think this is in cretaceous age but not sure. see other 2 posts   these samples are really interesting, found in situ, on exposed section of eroding sandy beach cliff - see photos, sand with layers of iron rich str