turtle-belly mound; bun-shaped plaster base
A traditional Japanese architectural feature: a rounded, white plaster mound resembling a turtle's belly, used to support base stones of buildings, lanterns, or monuments. Domain-specific term.
A turtle-belly mound is used for the base of this stone lantern.
Compound of 亀 (turtle) and 腹 (belly), from the shape's resemblance to a turtle's underside. The exact historical derivation is uncertain.