Shibi (鴟尾) is an ornamental roof ornament used on the ridgepole, called oonume (大棟), of the tiled roof of a temple or palace.
They are also referred to as kutsugata (沓形) since the shape resembles a shoe.
Often, they are in the shape of a sachihoko (鯱鉾), an animal from Japanese folklore who's head is the shape of a tiger and it's body is the shape of a carp. The animal was believed to protect against fire and bring rain.
Traditionally, shibi were made from tile. They were later made from wood and covered in a copper shell. There are also a few stone shibi in existence.
— History
Historically, shibi were very popular in China, as well as during the Japanese Asuka and Hakuhou periods. Popularity began to drop off by the end of the Kamakura period, however.