One of the ten plagues that Moses unleashes on Egypt in the Book of Exodus is to make the Nile river run red with blood (Exodus 7:20). My question is, is there any information, either in the Torah itself or in other Jewish scriptures or works, about the nature of this blood?
Was it human blood, or animal blood, or divine blood that bore no relation to earthly blood, or what? Now I'm aware that some people believe that this was a purely natural phenomenon, caused by phytoplankton or minerals or something else, but I want to know how the believers (that this was a supernatural event) view this?