Parasite

The parasite is an hostile deep-space monster. While being hostile to your crew, they also can be a danger to raider crews. Their favorite target are sleeping people. It has low hit points and can be punched to death by someone just fine. It's damage are random-ish; they can instantly kill someone as they can just fail at even scratching the skin. It needs to breath, so can asphyxiate, you can also force it in space to kill it.

They usually are met in some derelicts, and with new immigrants. In derelicts, it is likely that it used to be a ship, where someone was infected, the parasite killed the entire crew then and the ship eventually crossed your path. In new immigrants, you can possibly have one that is infected with the parasite, which will soon or late burst and kill the carrier, and then wander in your base to go on a rampage. You can find out if one of your crew members is infected with their log book. You will see messages such as: If you see one of those messages, IMMEDIATELY get rid of your colonist: that means he is infected. I recommend you try to suck him out in space to kill both him and the parasite without any risk, you can also lock him in a room and DELETE the door, he will either starve to death, or the parasite will burst out trapped with the dead body. If that happens, you can try to delete a floor tile to suck the parasite out. (NOTE: This has been made obsolete with the addition of medical staff. Now you can just send them to a medbay with a healing chamber) Parasites will be your worst enemy when exploring derelicts, as they can kill very quickly.
 * "It's normal that my guts are moving to my head?"
 * "My stomach skin is moving again, HAHA, that's super weird"
 * "It is possible for your organs to move around?"