Talking of cool, that is what caused the marks. They are stress fractures from the blank being too cool when struck. Like an earthquake when the ground splits, so could be called a coin-quake!
They wouldn't do - with millions made then most are alright. Just on the day that one was made the blanks were not hot enough; on that day, or hour. So could have been one of the last few on the end of a shift, or at the beginning. Not a die crack as that is one raised line, so the blank has cracked, minutely, from the force of the pressure.
My whole family is Suomi; my uncle Pekka is a coin dealer outside Helsinki.
He & other dealers have seen this before, & agree it's something to do with the annealing of blanks.
I think the "Rahapaja Oy" (The National Mint of Finland,Inc.) has something on their web-page about it.
Regards, Robert.
I have noticed that too and those coins are unc ones. I think that the manufacturing is the answer. By the way I do have some Finnish coins to swap. It is nice to hear that you think Finnish Lion coins are nice (I'm Finnish ).
The lion of Finland is a close nephew of ours, although for the time being, maybe the UN is taking that away too. (Don't know if you heard about the Zwarte piet dilemma). But I always like coins with the weapon of their respected countries on it.
Nordfljot Groningen-Friesland.
Referee for Dutch Republic, Netherlands and Frisia
). 
