It is believed that the fungus is an irritant, waking up the bats repeatedly and causing them to exhaust the body-fat reserves needed to get them through hibernation.

The reddish-brown stalk is made by a fungus called Ophiocordyceps unilateralis, which has invaded the ant's body and manipulated its behaviour.

And that moisture, along with the body and the food buried there, would have fed the wall fungus, until the tomb ultimately dried out.