Creatures were blind, used echolocation. There were different species who inhabited different depths, those on top knew about those who live near the bottom via tales from those beneath them etc. One dude had a stone from the bottom, there was a trade going on between those strata but they couldn’t meed each other because of pressure difference. One time thee is a big noise coming from the ice, bunch of creatures gather wondering what it is, the drill appears, it’s made of unknown to them material (metal). Dude with the stone uses it to “kill the beast”/cut the cable. People on Earth watch televised transmission from cameras on the drill, see the creatures and are amazed.

FOUND IT! It’s Through the Roof of the World by Harry Turtledove