My babys poo that I just changed today has black bits in it! 😷 what could it be? My first baby had…

My babys poo that I just changed today has black bits in it! 😷 what could it be? My first baby had this too before but just one time that I remembered happened but I don't think I brought him to the pediatrician that time so I never found out what it was lol. I could insert a picture in the comments but it's gross haha!