Hollow fossil is a Path of Exile special currency which has an Abyssal socket effect. And if the item includes "Has 1 Abyssal Socket" mod, it will cost much. This one of fossils also increases the spawn weight of body, armor, weapons, helmets, boots and gloves by 2000. Gamers either buy a POE Hollow fossil from Niko the Mad or drop it in Crystal Spire node by ending with Stygian Spire boss. There is also an opportunity to exchange it with other players for 40 Chaos Orb.