You should sell your Revolutionary War cannonball for 200 dollars on eBay and use the money to buy an iPhone.
No, your absentee father unearthed that cannonball in his basement and gave it to you. Treasure it forever.
It is of literally no use to you and could potentially harm your future children or, more realistically, cats. It will totally roll off a shelf and cripple one of them. Isn't it made with lead or something equally old-timey and dangerous? Get that thing out of your house.
These colors don't run.
You don't need a cannonball right now. You need an iPhone. If ever you wanted to patriotically display a cannonball in your home, you could just buy another one.
You can't buy this exact cannonball that your father gave to you. When he's dead in a few years, you'll regret selling that cannonball. It's the only thing you'll have to remember him by.
You're his first born. You will get more crap to remember him by when he dies.
If you had a cannonball you could do this to your enemies: