1. Potamopyrgus antipodarum shell found empty. Rusty colour may be result of oxidation of black deposit acquired in life. From freshwater pool with substrate of black anaerobic sand covered by few mm of reddish brown aerobic sand. Dee Estuary, Cheshire.
2. Potamopyrgus antipodarum shell found empty. Rusty colour may be result of oxidation of black deposit acquired in life. From freshwater pool with substrate of black anaerobic sand covered by few mm of reddish brown aerobic sand. Dee Estuary, Cheshire.

Potamopyrgus antipodarum shell found empty. Rusty colour may be result of oxidation of black deposit acquired in life. From freshwater pool with substrate of black anaerobic sand covered by few mm of reddish brown aerobic sand. Dee Estuary, Cheshire.