Answered by Redditor u/feric51:
Appears to be a German artillery fuse.
Do a search for HZ 05 fuze...
Answered by Redditor u/wings_of_wrath:
Artillery expert here.
First off, let me reassure you this thing is 100% inert. The bottom is heavily deformed and split, which means it comes from an exploded shell. Also the flame exhausts of the time platter are also burned and blown out. Besides, this type of fuze comes with a detonator attached to the bottom which is missing.
If anything, you now have a nice looking paper weight. Enjoy!
As others have already said, that is indeed a H.Z.05 ("Haubitze Zünder 05", or "Howitzer Fuze, model 1905") German artillery fuze, more specifically a triple effect fuze (timed explosion, percussion without delay, percussion with delay) designed for 10cm light field howitzers and used during WW1.
The top is made out of brass and the rest is made form an aluminium and zinc alloy.