Ichor

Ichor is a crafting material dropped by Ichor Stickers in the Hardmode Underground Crimson. It is the Crimson counterpart to the Corruption's Cursed Flame. However, it does not appear to be "unholy" or "evil" as its counterpart (see tooltip), but it could, though, be taken as the blood of 'evil' gods, such as Cthulhu (See Eye of Cthulhu and Brain of Cthulhu).

Tips
Ichor does not burn up in lava, so pouring lava on Ichor Stickers is a possible way to collect Ichor. This also means areas with lava can be used as natural traps to farm Ichor.

Trivia

 * Ichor, in Greek mythology, is the golden ethereal fluid that flows in the blood of gods and immortals, as also said in the item's description. It also means a discharge from wound or ulcer, which fits more to the disgusting theme of Crimson.
 * It can be pronounced "aye-car", "aye-kur", "ih-kor" or "ick-er".