I'm a printer.
If that's some kind of a plate, which it may or may not be, it would be a letterpress plate or die of some sort. It could be used for embossing as well. It's hard to tell for sure what it is from the picture.
If it's lead, the holes could have been punched out simply to re use the lead for something else. Lead can be easily melted down and recycled and it used to be done all of the time. It wasn't unusual to bust up and melt down old stuff to make new.
I work with some people who would know better than me because I'm not a letterpress guy. I'm an offset guy. It's a completely different process but we do still use letterpress where I work, but only for die cutting, embossing, foil stamping and scoring. Our operator has been doing this a very long time though and he would know. I'll try and have him take a look.
He doesn't come in every day so I can't say when. In the meantime maybe someone else knows.
How big is it??