Chia seed- like specks in baby stool

Baby has had blood in stool before. Was always bright red of course. We breastfeed and use alimentum rtf or more recently Nutramigen (not daily). Lately I have noticed 1-4 tiny pen point-like or chia seed sized black specks in his diapers. Doesn’t look like deep red/dark blood. Just plain black. Haven’t come across this before in literature. Baby’s GI is not really helpful.

Has anyone experienced this?