Be ware of rusty holes….
let’s say you stick your finger in it, and for argument’s sake ignoring the case about infection right now, you left it in there for like several years. Well after a few years, (10, 100, not sure) you’re finger might begin to feel some preasure because RUST EXPANDS! And if your finger was snugly in there in the first place, watch out! You might break some skin AND THEN GET AN INFECTION THROUGH THE RUST.
Due to cooperation issues, the best subjects for this experiement tend to be dead, which helps for the health and safety reasons since dead people don’t get infections, more or less.
I don’t know of this experiement with fingers but I know if your put this metal into a building…stone or brick, then you’d have problems because bricks are people, dead people in terms of movement. And they hurt when metal clamps within their walls expands. Don’t hurt walls, fingers, other builting materials….