A strange find

Curious to hear what other paddlers think about this. My paddling buddies and I found a small suitcase (the little kind you can pull behind you on wheels) floating in the lake today. It was too heavy to manipulate on the water, so we dragged it to shore.

Upon opening, we discovered a large, steel ball in a plastic bag (sort of like this https://www.amazon.com/RT-OSXE-Reflective-Decoration-Stainless-Floating/dp/B09FPC1NBH?th=1). Here's where it gets weird. The suitcase was loaded full of landscaping stones, like someone purposely sank it. Also, mixed in with the stones was an ornate key. The metal ball had two, large dents in it. Here's the actual ball we found: https://imgur.com/a/5WWI9Es

Normally, we find all kinds of things in Lake Erie, but I find it kind of disturbing that this was intentionally sunk. Why not just throw it in the garbage? Very odd!