Found in the Forest

When Frederic and his dad went mushroom hunting in the forest a week or two ago, Frederic found this item in the forest. It is made of metal, about 11 cm long, and very rusty. Any ideas on what it is? (This is not a riddle, as we don't know the answer!)

Some people have guessed a hammer, but it seems much too small for that unless it was one of the seven dwarfs' hammers. Others have suggested a railroad spike, but it's much larger at the end than at the top, so I don't think so.

There was a lot of WWI fighting in our forest, and some WWII fighting as well, so our guess is something from one of the wars. Frederic's coworkers think it is a leftover piece of a bomb. We could clean it up so we could see it better, but I'd like to be assured it's not going to blow up in our faces before we attempt that.

What is your guess?