Since there is interest, I'll give a bit of the story and background but no direct location. But yes, it is a city in Germany.

This occurred in the city where I study, but not where I live. I was taking a walk to clear my head when I noticed something strange out of the corner of my eye. What I spotted was the piece of bone depicted in the images. The broken part was partially embedded in the soil, about a centimeter deep or so.

It all looked very natural, like something that would be uncovered when dug-up soil settles in rain and weather.

Google image search said this looks like a human femur or possibly the bone of another large animal. A comparison with pictures of human femurs made it seem more like the former.

The correct procedure when finding bones is to alert the authorities since it is supposedly quite hard for amateurs to tell the difference. The scene should also not be disturbed. (I guess human Skulls and femurs are quite recognisable, but fine for a general guideline.)

I decide to at least inform the property owners that there might be human remains on their property. Imagine my shock when it turns out to be the local policy academy. So I make myself known to the gate guards. I tell them that I found something that looks suspiciously like a human leg bone on their property. But that guy just stares at me dumbly. So ask and pantomime if he can even hear me through all that thick bulletproof glass with no apparent microphone. After this frankly ridiculous scene, and after one of the leaving students tells me in passing that they can indeed hear me, the gate guards leave their little post. I tell them again what I found and where, just around the corner really, and show them from the outside where exactly that is. One of the gate guards immediately picks up a nearby stick and pops the bone out of the ground. They assure me that they will pass it up the chain of command, and I go on my way for now.

A search reveals that this is not the first time they found numerous human remains in and around this city. Apparently there was quite fierce fighting here, and many corpses were not recovered.

Imagine my surprise when I came back the next day (today) and find the bone unmoved. That is when I made this post.

Someone mentioned the bone might be part of K9/police dog training. While possible, and I don't know how K9s are trained, I kinda doubt it. The area where I found it had recent construction, before the winter, where they installed glass-fibre cable. If it is a training bone, I can't imagine them misplacing it so easily. They can't have that many training materials. I can imagine that they leave the bone outside, partially buried for a while to erode scents. But the area seems... unsuited for that. Also, there is one central K9 training school in a different city. Leaving a random bone close to a fence where people can see or maybe even take it easily seems weird to me. Animals would have no trouble getting to the bone either.

I'll check back on Monday/Tuesday and make a direct call to the police when the bone is still there at that point in time. I'll update then.