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The sima runs around all four sides of a building. The raking sima is continuous, while the simas on the other sides are broken by downspouts. Early simas feature tubular or half-cylindrical spouts, but these were mostly replaced with animal-head spouts by the middle of the 6th century BC.
Simas may be made of terracotta or stone.
Simas are normally decorated. Stone simas have continuous narratives, especially on the raking sides where they are not interrupted by spouts, similar to a frieze. Terracotta simas have repeating patterns that are easy to reproduce with molds.