What i got from a very old bucket well at my house

I got a rock slab from it and I think that it is very rare, I couldn't find another one on the internet, they put a well in so I am assuming it was neuro typical and it is old and I don't know anybody who uses bucket wells around this area and my mom said that this one is at least 70 years old maybe older we really don't know how old it is. We just know that it was there all my mom's life and she is 61 yrs old. If you didn't know this wells are what people got water from before they had running water threw pipes