Fossil clam shells along the beaches of the Colorado River delta, Mexico. Before upstream water diversions, clam populations generated higher carbon emissions than populations today. Photograph by Jansen Smith. See Jansen A. Smith et al., Fossil clam shells reveal unintended carbon cycling consequences of Colorado River management. R. Soc. open sci. 3: 160170. http://dx.doi.org/10.1098/rsos.160170.