most of these clay lamps were shaped using moulds in workshops that turned out large numbers of standardised products. some of the most popular forms incorporated a central ', a circular area usually around 4–6 cm. in diameter, that incorporated the filling-hole and could be ornamented with pictorial motifs in low relief. the range of decoration included pagan deities, myths and legends, genre scenes from everyday life, animals, hunting, public entertainments such as gladiatorial combat and chariot-racing, erotic encounters, and in late-roman times, some christian symbolism: in short, the full range of subjects that occur in the roman decorative arts (jewish lamps with symbols such as the menorah are also found). types and decoration initiated at the centre of empire, in italy, were often imitated in products made in workshops located in other provinces. lamps could be directly copied by the process known as ', using an existing lamp as the archetype for producing the mould, rather than creating a hand-modelled clay archetype.