Killer Sells appear as balls of flesh with multiple arms, which they use to anchor themselves to the floor and ceiling. Some will already be anchored when you meet them, while others will bounce around before anchoring themselves. Outside of that, they don't have any other form of attack. Upon being destroyed, their arms will dissolve into green projectiles.
- The word "Sell" is likely a mistranslation of "Cell". This is further supported by the nature and shape of the enemy.