Excellent Detail
Excellent face-on detail of coral fossils, as seen embedded within the rock of the Opal Member of the Mount Head Formation, Rundle Group, Peter Lougheed Provincial Park (near Aster Lake). The rock itself is something along the spectrum between limestone and mudstone (maybe marlstone?). Geologic period: Lower Carboniferous, roughly 350mya. I believe the white streaks on the left are occurrences of chert.