I'm wondering if this coin is severely debased currency or a copper fake. It simply looks too much like copper and dipping in eZest coin cleaner only slightly brightened it with no change in the tone.
I'm thinking fake, the out edges of the coin have a very sharp edge to them as if it was cast or pressed. Almost looks like a modern cent with its sharp details.
Fake. Check out this link to wildwinds.... https://www.wildwinds.com/coins/ric/geta/RIC_0088_Fake.jpg
Here is my real one. Geta (209 - 211 A.D.) AR Denarius O: P SEPT GETA PIVS AVG BRIT ,laureate head right . R: LIBERALITAS AVG V , LIberalitas standing left with counting board and cornucopiae . Rome Mint, 211 A.D. 3.7g 18mm RIC 88, RSC 68 The reverse ends legend with "AUG V". The 'V' stands for the number of times donatives had been given at the time of the minting. "Liberalitas" signifies generosity.
There are limes versions in bronze. I suppose if you doused this coin in naval jelly it would turn really bright copper colored like that.
So, the person I bought it from says it is an "AE" Denarius, which means it is copper or bronze. I read that these type of coins were struck or cast, some may be contemporary fakes. They also claim to have cleaned the coin themselves. Would you think it is an ancient coin or modern reproduction? See https://www.forumancientcoins.com/numiswiki/view.asp?key=Limes denarius
Modern. In addition to the Wildwinds link above there are multiple other examples on Forum Ancient Coins if you search the fake reports for "Geta 88".