Help Identifying Possible Roman Coin

Late Roman bronze of an emperor, maybe Constantine II. I think reverse is globe on altar. Your pic has it upside down. Can't see mint mark if it's still there. You might find a match on Vcoins.com or other ancient coin sites.

You can use the search line here on CCF and your internet browser, how to clean ancient coins. Your coin is in bad shape, not worth much, you won't affect the value by cleaning it. But in my opinion it's not worth cleaning unless you want to for fun.

Yes the reverse is BEATA TRANQVILLITAS (blessed tranquillity) - an altar inscribed VOTIS XX, with a globe on top.

The obverse has the letters CONSTAN, so it is Constantine I or Constantine II.

There are many variations from Londinium, Lugdunum or Treveri https://numismatics.org/ocre/result...et:%22AE3%22