Through a small rocky hole, archaeologists could feel the air — could tell some unknown space lay just beyond their reach.

They pushed through the sealed up a passageway and shined a flashlight around the cavern.

What lay before them exceeded all of their expectations.

The archaeologists in Spain were exploring the underground caverns of the Cueva del Arco when a particular spot caught their attention, according to a Friday, Feb. 3, news release from the University of Murcia.

The sediment-filled spot seemed like a sealed up passageway into another cavern.

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The spelunkers began to excavate, slowly and painstakingly, hoping they’d find something to make the effort worthwhile.

They dug into the rocky cave wall, and air began coming through the hole.

Read more: Miami Herald