Most likely residue from a degraded holder. I've seen this on a lot of coins. It's kind of waxy and comes off with a toothpick.
1) Token of some sort. 2) France, 1918 5 Centime. 3) Ukraine, 1992 5 Kopiyok. 4) Egypt, 1916 5 Milliemes. 5) Sweden, 1668 4 Ore.
Separate names with a comma.
