What is this?

Shelly • Mama to 👦🏼 Jesse 6/4/19 & 👶🏻 Jameson 3/11/22

When I went the tech found it very quickly and didn’t spend too much time finding out gender cause she was certain it’s a boy 😂. I know he’s a boy but what’s that dark spot? Is it just a shadow or the way the picture was taken? Seeing everyone’s potty shots now has got me wondering what it is?