It's a fantasy role-playing game.

DM: You are Fjord, a half-orc warlock . You are the member of the famous group of adventurers. Previously, Avantika had a head start on you, but he managed to catch up and reach the end of the tunnel at the same time as her. The two began to scrape grime off the floor.
DM: As the two of you are currently scraping bits of grime and algae off the ground, there are bits of plants that are growing up like lightless kelp that seems to have made some sort of a living down here in this subterranean, water-filled chamber. As you're pushing through and scraping around, your hand scoops this large bit of grime from in front of you and you can see a stone relief at the very base of the bottom, a concave, spherical shape about the size of a fist.
Player: Uh huh.
DM: She notices it, looks at it, looks at you. What are you doing?
Player: Could I try and stick my hand in my chest?
DM: You can.
Player: Does it go anywhere?
DM: You go and jam your hand and its hitting your armor. You have a full-on leather plate right there.
Player: I don't know what to do. Like the size of a fist? It's a sphere, right?
DM: It's about that big, and you can see it is concave. It's about the size of the stone that you'd found.
