Researchers in the Netherlands have identified a smooth, white Roman-era stone as an ancient board game, using AI to help reconstruct its rules.

The circular limestone features straight and diagonal lines, with wear patterns suggesting pieces were slid along them.

Scientists at Maastricht University trained an AI program called Ludii on 100 similar ancient games, which generated possible rule sets that were then compared to the stone’s wear.

The game appears to have been a strategy contest in which players aimed to trap opponents’ pieces using glass, bone, or earthenware tokens, CBS News has reported.

While researchers caution they cannot be certain Romans played it exactly this way, the findings provide a likely explanation for the stone and were published in the journal Antiquity.