This is a container for small things, looking like a mushroom. Typical use is for geocaching, since the room inside is rather small.
Print one of each of the stem and cap, then assemble by screwing them together. The stem has a "secret" room inside, approximately 5 cm deep.
The stem is chamfered at the bottom, and it also has a 4 mm hole where some kind of spike might be mounted. I used a piece of a threaded 4 mm rod, which I filed at the end to make it sharp.