Restored cup from the Royal Pottery Stores. Evans suggested that the decoration imitates breccia, a type of sedimentary rock.
Bibliography
Evans, Arthur. 1921. The Palace of Minos at Knossos, I, p. 238, fig. 178
Myres, John (ed.). 1936. British Archaeological Discoveries in Greece and Crete 1886-1936, p. 16