"What sort of giant manthing carried a forty-stone chrome satchel on their shoulder? The answer is not known. But a clue is stenciled on the side of the satchel: a drill pointing downward into a well."
When activated, a stairway down is created where you are standing. Sometimes the way down will be blocked, but using the item again clears the space. Sometimes a stairway back up on the floor below is not created, for unknown reasons.
There are a limited number of uses, but the number of them is unknown. After they're all used up, it disappears without any message.
"The metal satchel opens, folds itself inside out, and transforms into a contraption studded with pinions and drills. It starts to burrow into the ground."