Green Blood Corpuscle

I have never heard of a Green Blood corpuscle. My kid is 100% sure that just like a red or white blood cell, the green blood cells exist. I could not give him an evidence against his belief. On googling, I learnt that although mammals and few animals have Red blood, some animals like crabs, crayfish, octopus, squids etc have blue blood and some marine worms have green blood!!( yuck- remembered Shrek, the ogre). People who are overdosed with sumatriptan can have their blood turned green, as a result of sulphhemoglobinemia!!