There are some on the mk 4. I think they were tie down points on board ship.
Personally I would remove them, treat any rust, and ,assuming its not going to show too much, spray some underseal or stone guard spray then refit the grommets before it dries. Otherwise they might drop out. You could also spray over the top -belt and braces. Its best not to go mad with underseal as it can attract the attention of MOT testers.