Imbrication or petal diaper, i.e. ornament resembling shaped roof-tiles or the scales of fish, often found on Antique sarcophagi-lids. The best-known example is the top of the Choragic Monument of Lysicrates, Athens (334 bc). In its simplest form it is a pattern of several series of semicircular forms, each row staggered with the centres of each semicircle on the junction of vertical lines struck from the points on which the semicircles spring and other horizontal lines drawn across the top of each arc.
Lewis & Darley (1986)