I was searching for curiosities on the web and i find this thing : the number of viruses and one-cell beings know by man reaches almost 5,000,000,000,000,000,000,000,000,000,000... big number no ?,everyone know that a single virus can exterminate all humanity.examples ?. The Black Plague,XIV century,25 to 75 millions were killed by the virus...and we have 5,000,000,000,000,000,000,000,000,000,000...and this number is just the ones the humanity knows...