What could this have been?

I found this in a very unused section of a park, that was a hospital late 1800s-early 1900s.

According to this chart it’s lead.

Here’s the pics...


And it weighs...
or for you gram lovers lol

Any ideas how to get the crud off it? Without filing it looks like sandstone with a black outer crust.

Any ideas?


Bounty hunter - treasure hunter - cabelas special edition.
Best find to date - 15g platinum ring
Total clad 2018 - 45$