Man-made underground passage in Cooracurkia

That is the place in Cooracurkia. It is a shallow D-shaped depression, roughly centrally located inside a possible rath. Local belief calls it the blocked entrance to a cave, suggesting people once cut or cleared a passage beneath the mound. The chamber may have stored grain, hidden people or simply let the owner escape rain and heat. Whatever it did, the earth closed the mouth while the purpose faded from memory.