A mysterious stone monolith jutting from the ground near Manchester, England probably served as a crude seasonal calendar for Stone Age farmers.

The moss-covered monolith has three faces and appears to be roughly 4,000 years old, based on dating of other relics sprinkled about the site, which is called Gardom’s Edge.

Rather than a precise sundial, Brown thinks people used the 7.2-foot-long monolith to “enhance the importance of the site for seasonal gatherings or ceremonies.