Our house had one of these slots. When we remodeled the bathroom there was just a huge pile of razor blades. No water damage or mold, just a pain in the ass removing those walls since it was those small slats with nails and cement (I think it was cement?). Just lucky the only asbestos was on the pipes in the basement.

I got a can of chicken broth, knocked a slot into the top with a flathead screwdriver and a hammer, poured out the stock and rinsed and dried the can. It lives in the cabinet beneath my sink and I drop my blades in it when I'm done with them. That was about 10 years ago. The thing is maybe a third full.

Wall filled razor blade FAQ

I am living in your walls. You may be concerned about this. In case you are, please read the below: FAQ: Why are you living in my walls? I'm not going to tell you. Are you only in my walls? You could say I am living in everybody's walls, but in the case I am telling you that I am living in your walls, I am living in your walls. How are you surviving in my walls? In my non-physical form, I am crawling around listening for you. That is all I need to survive in that form. In my physical form, I survive by eating rat corpses that I cook using the wall behind your oven, and I drink the vapour in the extraction fan duct above your shower. What are you planning to do in my walls? Live in them, listening to you. What do I do about you living in my walls? Listen for the scraping. Dont touch the walls. Protect yourself. Avoid lighting candles. When are you going to stop living in my walls? You cannot escape me. Do I call the police? The authorities will not help you. What are the consequences of you living in my walls? Be aware. What if I am ok with you living in my walls? I will make sure you’re not. Are you imaginary? I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS I AM LIVING IN YOUR WALLS If there are any more questions then please consult your walls by directly speaking to them. Summary: I am living in your walls.