ABSTRACT
With the exception of the most primitive forms, all ecphora shells have a thick calcite outer shell layer, often colored bright reddish-brown or yellowish-tan. This resistant outer shell layer prevents dissolution by groundwater, often making ecphoras some of the only fossils to survive in heavily leached deposits (such as Shattuck Zones 12 and 14 of the Calvert Formation and Shattuck Zone 20 of the St. Mary’s Formation).
