I am from the Dutch-speaking part of Belgium, and this popped into my head today. Is the word acorn (the nut of an oak tree) in any way related to the Dutch word for squirrel, eekhoorn, the animal that collects acorns for food?
Looking at eekhoorn, one will have a hard time finding any logical meaning to the naming of this animal. There's eek, which is not a Dutch word, and hoorn which means horn. So it doesn't make much sense. But the pronunciation even in Dutch/Flemish is remarkably equal to the English acorn.
Since many words have migrated country borders (like the NL bolwerk and EN bulwark), I wouldn't be surprised if it's the same with acorn/eekhoorn, except for the fact that eekhoorn is the actual animal that consumes the acorns. That would make it pretty unique, I think.
By the way, acorn in Dutch is eikel, having different connotations which I won't explain here.