Blood is cool because it like, helps us live and stuff (I have a medical degree). But when you're dead you don't need it. Same goes for cows, which is why somebody decided to be all WASTE NOT, WANT NOT and started baking bricks out of the stuff. Blood bricks, brobro. They should make booger ones too. Reduce, reuse, or wipe under your desk.
Animal blood, specifically cow blood, is "one of the most prolific waste materials in the world," according to a recent U.K. architecture school grad by the name of Jack Munro. Munro decided to try and figure out whether cow blood could be used for anything architecture-y. After experimenting with making glue, he found that by mixing in some sand (and a preservative), and then baking that for one hour at just 160 °F, you can make waterproof and structurally passable bricks.
No word what would have happened if the third little pig had built his house out of blood bricks instead of regular ones, but my guess is watch the big bad wolf slowly eat a hole through a wall before being torn limb from limb. Sucks for you, homey -- I built my house out of CANDY (I'm banking on the wolf succumbing to diabetes before he gets to me).
Thanks to Saman, who actually suggested making bricks out of OTHER bodily fluids. Perverted ones. I deleted the email.