Opus scutulatum

Opus scutulatum, literally "shield work", is a type of masonry construction used in Roman architecture.

It consists of irregular chunks of stone or polychrome marbles on a background of white tesserae lacking figural decoration.

[1] A mosaic floor in opus scutulatum, also called crustae or lithostroton,[2] consists of an almost always monochrome background with inlaid larger scutulae, literally “shields”.

The fragments exist in many shapes; in addition to rectangular ones, triangular and diamond-shaped stones are common.

[3] Pliny (Naturalis Historia XXXVI.185) reports that opus scutulatum was first used in Rome at the beginning of the Third Punic War (149 BC) in the Temple of Jupiter Capitolinus.