There were quite a few of these that spawned during the invasion. For a while, the moongate went haywire and would absorb the corpses of daemons around it, causing them to decay quicker. When this happened, there would be pools of blood everywhere... some of these blood pools, hued a darker red than the regular blood, were able to be picked up. I personally collected enough to make 10 full sets (of 1 of each of the 6 available graphics) with plenty more left over to sell on my vendor. Initially I had the single pools selling for 200k and full sets for a million, but once they stopped spawning, the prices skyrocketed on Pacific. Now I have a few of the pools on a vendor for 500k each and still get decent sales from them on occasion. Hope that helps.