They were inside an ancient La Roche-Cotard cave in ... During the process, researchers also spotted carvings made by claws of animals, like cave bears, and through metal during modern incursions ...

Once a hefty amount of soil was heaved out, something extraordinary was revealed: masses of intricate carvings covering the walls, representing humans, animals and full historic scenes.

Beneath this inflating membrane, the lava continues to ooze, eroding the ground beneath it and carving underground ... lava caves out of respect for what they might encounter inside.