There is two types of world bosses
SS rank hunts who require specific spawn conditions and don’t appear on the map, these are denoted by the line in chat “you sense the presence of an incredibly powerful mark”
The other is fate chain Enders. They are technically fates but they are functionally the same, being world bosses that require specific spawn conditions and that have long CD’s. That snake, chi, Odin are all examples of fate world bosses
That snake is not in any way shape or form a normal fate