The seat belt buckle is held above the floor by a little plastic button that is riveted onto the seat belt at the right height. The plastic button is black and visible in the middle of the belt towards the bottom of this picture.
Sometimes, it breaks off. Thereafter it can become difficult to find the buckle, because it can slide along the belt all the way to the floor.
I first tried a safety pin for awhile, reasoning that the small hole in the belt must not be a safety hazard because the hole is there for the original equipment button in the first place. However, when the safety pin comes undone, it can cause some damage to a questing hand.
So, I used a large keyring. Carefully starting it through the pre-existing hole in the seat belt, I worked it around until it was entirely in place, encircling half of the belt. It is clearly visible around the right half of the belt midway down the picture.
This works very well, and the questing hand can find it easily, and without injury.
Imaginary insects based on Star Wars characters
27 minutes ago