Looks like something mildly acidic got spilled on this coin. You can see the "tide line" of removed toning, running from the beginning of the N in ONE, over in a wavy line to beyond the T in CENT.
The red stain might be just the salt deposit left behind when whatever liquid it was, evaporated away. Or, it's entirely possible that the "red stain" was originally a green stain of corrosion, and the "tide line" is the mark left behind from whatever cleaning agent (like ammonia) was used to try to make the corrosion go away.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis