Egg Capsule Center
Thing type 291, Egg Capsule Center, is a type of Thing that is used to spawn flickies from an Egg Capsule. There are two ways to activate an Egg Capsule Center: One is to give a sector the Egg Capsule type. When a player steps in this sector, all Egg Capsule Center Things in the level will be activated. The other method is to use a linedef executor with linedef type 464. In this case, the tag of the control linedef should be equal to the Angle value of the Egg Capsule Center Thing that is activated. Note that the Egg Capsule itself is not automatically opened when the Egg Capsule Center is activated. See the Egg Capsule tutorial for an explanation of how to set up a functional Egg Capsule.