Board Thread:General Discussion/@comment-32040058-20170518111335/@comment-33883848-20191008061724

He has a skeleton thus yeah he's obviously a skeleton.And skeletons don't bleed because they have no biological body and thus i think the "blood"is ketchup.However,i do think that Sans wasn't always a skeleton,to me he's just a ghost haunting a human skeleton just like Papyrus as it explains how they were made as skeletons don't have reproductive parts.