Horse bones and red deer antlers dating back 1,500 years have been found on Galway beach. Experts believe the marks on the remains indicate the bones and antlers could have been used for a ritual ceremony.

Brian O’Carra and Mike Williams discovered the antlers, skulls, jaws and bones of the animals on an inter-tidal zone west of Galway city, the Irish Times reports.

They believe the antlers came from young, sexually mature stags. Only one species of red deer could be found in Ireland at that time. The horse bones are believed to have come from a small young horse and an older horse or pony.

Radiocarbon dating on one antler indicates it dates from between 430 AD and 548 AD.

Professor Williams said that cut marks found on the bones indicate the animals were consumed as food or ritually sacrificed. This was at a time when Christianity was already taking hold in Ireland. Williams says eating horses would have been forbidden at the time, making the evidence even more compelling.

Williams and O’Carra have worked together to chart how Galway Bay was once a region of lagoons and forests before the sea level rose thousands or years ago. After having examined the area where the remains were found embedded in black silty mud containing shells, they believe “significant environmental changes” may have occurred as recently as 1,500 years ago.

Williams and O’Carra say that the site requires “organized archaeological excavation” and that both the National Museum of Ireland and the Office of Public Works have been notified.