Okay, I went with igneous stones. You may laugh.

Kpingnis seems less like a weapon and more like a coral reef. I know. Heck, it's ironic that this was found in a coral reef ecosystem.

However, its power is not to be underestimated. Orangusnake had the gall to underestimate it and got both parts of his body (the orangutan and the snake) to fuse. Indeed, it can restructure your bones and even leave holes in it if the wielder so much as wished for it. I nearly got myself fused with Beumarrang. That... Would have been an interesting situation.

Either way, it's irreversible, yes, but it's also pretty fragile for a normal; fighting against a weapon on fire would melt it beyond recognition. It takes SO long for it to grow back to its normal form so I refrained from using it.