Egg sacs, also referred to as "Hunter traps", are pustule-like growths that appear around the Ship if the Hunter is the monster. Although harmless in and of themselves, they have a chance to "trigger" when the player comes near them, causing the Hunter to burst out.
Curiously, this means that they are only dangerous from afar, but are effectively inert if the player manages to get close to them without them triggering.
Note that egg sacs do not spawn multiple Hunters; there is only ever one Hunter in the game at a time. Because of this, egg sacs will not appear if the Hunter is currently roaming on foot or actively chasing the player.
Cargo Hold Edit
Unlike the egg sacs that appear throughout the rest of the ship, the ones found in the cargo area are static and do not de-spawn after being triggered.
- If the Hunter is "in the area" (indicated by the ambient squicking sounds it makes), but not roaming outside of a vent, egg sacs may form along the walls or ceilings outside of rooms in great numbers. This can be shocking, and can occur as quickly as it takes to enter a room and come back out. If the player leaves the area and comes back later, the egg sacs will be gone without a trace.
- It is unknown how the Hunter is able to place these formations without physically emerging out of vents and doing so. It is also unknown how it can "teleport" from egg to egg, and keep its body.
- Unlike the Hunter, egg sacs are immune to fire.
- Triggering an egg sac with an item is the objective of the Bait 'N' Switch achievement.