2005 Lincoln ?

Hi domys - I'm not an expert, but I've seen plenty of 2005 LMCs. The dot is likely a bubble under the plating (which looks split or open to the environment). Our LMCs from midway through 1982-to-present have zinc cores and copper plating. If the copper fails even microficially, the split/hole allows the elements in to do their nasty best (destroy the coin). The dot/bubble is probably the early stages of zinc rot, or officially known as hydrozincite. Under a microscope you can normally see the little white nodules of hydrozincite growing under the plating, lifting it from the substrate zinc core.

Size looks thinner/smaller, but probably within specifications. If you way the coin it should be around 2.5 grams.

Don't EVER push a suspected Plating Blister with a toothpick if the coin in question is a collectible date or variety. I damaged a good coin doing this once. Better to leave it alone rather than to risk damaging the coin. In this case you have a common coin so Coop's suggestion is just fine. You have nothing to lose.

I purchased a roll of "Save Our Cents" tokens that were struck over new Lincoln cents (this was maybe 1994) and a year later they had all developed a bunch of tiny plating blisters that weren't there when I bought them. Just a thought and Coop is right. Try to buy them without the blisters if you can. On the other hand some coins are so rare you take what you can get and then hope to upgrade.