If this rubber mat is placed on a smooth surface, it is very difficult to pull it off using the hook. In fact objects can be moved using the hook. Yet if the edge of the rubber mat is lifted, the mat comes up easily.
What is happening? The rubber mat prevents the air from rushing in at the edges, unless you lift it at the edge or it is on a porous surface. Hence, the full weight of the atmosphere above holds it down.
Since every square inch of atmosphere weighs 14.7 lbs and the rubber mat is 10.5 inches on a side, we calculate the force needed to pull the mat up by the hook. The force is (10.5 inch)(10.5 inch)(14.7 lbs/inch^2) = 1620 lbs. Amazing. I'll bet the hook would pull out of the mat before that force is reached.