First time accepted submitter calinduca writes "Artificial blood that could one day be used in humans without side effects has been created by scientists in Romania. The blood contains water and salts along with a protein known as hemerythrin which is extracted from sea worms. Researchers from Babe-Bolyai University in Cluj-Napoca, Romania, hope it could help end blood supply shortages and prevent infections through donations." Wikipedia's entry on hemerythrin
explains its unusual oxygen binding mechanism.