Foundation of a Mississippian carbonate mound

Thin section photomicrograph (image 2.5 mm wide), part of an ancient carbonate sand shoal. Later, a small mound grew on top of the shoal. Ooid grainstone.

A picture of a very small fossil

Crinoid columnal in Mississippian fossil deposit, coated with two layers of calcite (dark rim). The fossil is in a former carbonate sand shoal that buried a mound made of corals, bryozoans, and crinoids. Photograph about 2 1/2 mm wide.