Photos on phone dated before purchase date?

[Tela Wright]

Hello.... recently I found a photo on my phone that is date stamped before I purchased my phone and it's a picture of some random guy's genitalia . I know I personally didn't take, receive or download the picture. I'm so confused as to how it could have gotten there before I purchased the phone. Oh, and I bought the phone brand new. It wasn't pre-owned.