If i started my period and you had a blob come out it didnt really look like baby but did have big black dot at the top could been an eye how do know if was or not?

It is not possible to determine if the blob that came out during your period was a baby based on the presence of a black dot. Many things can appear in menstrual blood that may resemble parts of a fetus, but unless you take a pregnancy test and it comes back positive, its unlikely baby parts came out of you when getting your period.