Cadlina laevis has unobtrusive very small soft tubercles, a flattened low profile, a white shiny body with opaque yellow or white marks near the periphery and, sometimes, an opaque yellow or white peripheral border. It can retract its gills completely into a small pocket. It seems reluctant to extend its gills as the great majority of C. laevis images on the web have them retracted out of sight.  Scotland, April 2009, © J. Anderson.