The "gear" thingy is the fossil segment of the stem of a crinoid or blastoid type sea creature.
Likewise, the "leftover weapon" is probably a silicified fossil of some type of linear sclerobiont (hard substrate dweller via attachment) or remain of somehting like a belemnite.
The natural world easily provides a trove of things that look like a manufactured item, and Occums Razor would have us at the least explore the already profound concept that this was fossilized life on another world (not to mention the fact that, given it's tenacity, it probably still exists there deep below the surface in warmth and moisture).