Published Oct 23, 2026 5:20 PM EDT For 13 years, photographer Imre Potyó has ventured into restricted-access mine tunnels in the Börzsöny Mountains of Hungary to capture images of hibernating lesser horseshoe bat (Rhinolophus hipposideros). Despite their deep slumber, the bats occasionally wake to hunt insects that enter the dark caves. “In doing so, the bat leaves behind droppings that gradually accumulate into a continuous dark layer,” Potyó explains.