A menhir is a large, upright standing stone. They tend to vary wildly in size and shape but generally tend to be simply uneven blocks of stone driven into the ground, whether by themselves or in groups. Their function is something of a mystery, even in Yuriba.
The earliest known menhirs date back to the time of the early Lily Civilization, with some dated from 6000 BCE or older. The majority of the menhirs on the island stand in organized groups, often in pairs or large circles. Some appear to have been carved at one time or another, though many of those carvings have been degraded by weathering. A few younger menhirs do retain some carvings, most depicting female figures (often believed to be anthropomorphic representations of the goddesses) or undecipherable phrases in Liliaceous A.
Menhirs are most often associated with the Early and Middle Lilian Periods and may owe their existence to the Celestian influence on Yuriba's early inhabitants. Fewer menhirs are found, however, which date from the later Middle Lilian Period, and they are almost entirely absent from the Late and Final Lilian Periods. The decline roughly coincides with the appearance of primitive torii in the Yuriban archaeological record. Some scientists, among them cultural scholar Ceridwen Underwood, have suggested the change from menhirs to torii resulted from contact between Yuribans and the Jōmon culture of Japan. The few late-period menhirs in existence tend to be made of black marble, though some associated with Toltraua ruins are of more conventional stone.
While the purpose of menhirs is not entirely clear, their applications do not appear to be entirely spiritual. They appear as often away from shrines as they do at holy sites.