In Ray Bradbury’s The Martian Chronicles, the martians descend into and hide within caves after the humans arrive to colonize their planet. As in fiction, so in real life: this cavern, discovered by the Mars Reconnaissance Orbiter still circling Mars, and protected as it is from the acrid surface, might stow away Martian life. NASA scientists write that this hole maws to 35 meters, and that the cavern’s surface appears to be 20 meters beneath the surface.

Below, recent Pictures of the Day: