unidentified item in chia seeds : mouse droppings or something else ?

I have find an unidentified long black cylindrical grain-like item in my chia seeds, which had been soaking in plant-based milk for more than 48 hours. I had already eaten some of the soaked seeds from the same bowl yesterday. I didn't think to take a photo before handling it, cutting it, and deforming it, but here are some older posts showing the same situation, for reference:

https://www.reddit.com/r/whatisit/comments/1hkpvog/i_keep_finding_this_in_my_chia_seeds_maybe_2_to_3/

https://www.reddit.com/r/foodsafety/comments/1nnunym/is_there_freaking_mouse_poop_in_my_chia_seeds/

I immediately suspected it might be a mouse droppings, so I placed it on a towel and put on latex gloves to handle it. I tried to crush it between my fingers, but it stayed hard; by pressing hard with my fingernail, I managed to leave a mark but couldn’t split it in half. I was able to cut it in half with a serrated knife. When I press it against the towel, it leaves faint black marks.

I’m posting this because the previous posts haven’t been resolved. Many comments identify it as a mouse droppings, but others respond that mouse droppings would be softened or dissolved in water. I haven’t found any information online about how mouse droppings react to water. Several comments suggest handling the item with gloves —as I did—to see how it reacts, but they don’t explain how a mouse droppings should or shouldn’t react!

I just need to know if it could actually be a mouse droppings and if I should throw away the whole package or seek medical attention.