Cave spider, Deer Cave, Borneo. The spider is crawling over its web. Beneath the web is the carcass of a dead bat. Deer Cave in Borneo is the world's largest natural rock chamber. It is home to millions of bats. Their droppings collect on the cave floor and build up to huge heights. The droppings support a whole ecosystem of animals, described as troglobites, that live exclusively in the darkness of the cave.