Roughness, wrinkliness; see Donovan (2002) Geol. Today 18, 4 on rugosity in karst landscapes, and Knudby et al. (2007) PPG 31, 4 on coral reefs. In ecology, more rugosity will provide more available habitat for colonization, foraging, and shelter.

http://ccma.nos.noaa.gov/ecosystems/coralreef/coral2008/ Monitoring of coral reef ecosystems.