What made a snail have blood?

Answering here assuming you mean why snails have blood. Blood is, in terms of function within an animal, a fluid that carries gases (like oxygen) and nutrients required for cell of the body to function and carries away waste (like carbon dioxide) produced by the cell during respiration. read more

The blood of a snail is blue as a result of its blood pigment, haemocyanin. This pigment contains copper, which helps to give it a blue color. Human blood contains iron, which gives it a red color. The blood is colorless until it is oxygenated. Lobsters, crabs and spiders also have blue blood. read more

Most snail blood is blue-ish in color. This is because their blood cells use haemocyanin, which gets its blue color from the copper that is part of its structure. The Common Ramshorn Snail actually has red blood, because, like humans, it has haemoglobin (which uses iron instead of copper) in its blood cells. read more