The hollowed cave, called Umm Jirsan, is a sprawling lava conduit system underneath the volcanic fields of Harrat Khaybar in the northwest of the country.
Umm Jirsan extends for a staggering 1.5 kilometers (almost a mile), making it the longest known reported lava tube in Arabia. Within those extensive shadows, wild creatures have been busy.
In a new study, researchers report the discovery of hundreds of thousands of bones belonging to at least 14 different kinds of animals, such as cattle, horses, camels, rodents, and more. And some of those bones are human.
"This 1.5 km long lava tube is chock-a-block with hundreds of thousands of beautifully preserved animal remains," zooarchaeologist Mathew Stewart from the Max Planck Institute for Chemical Ecology in Germany posted on Twitter.
According to the researchers, this massive horde of bones was most likely scavenged together by striped hyena (Hyaena hyaena), whose own skeletal remains were also found in the cave, along with their fossilized droppings (called coprolites).