Thing type 138, Banpyura, is a purple crab enemy and a variant of Crushstacean. It is unused in SRB2's official levels. This enemy slowly walks from side to side within a small territory, and is armed with a special purple spring aimed toward a nearby player. If a player tries to attack a Banpyura from its sides, they will be bounced away by the spring, so it must be either jumped on top of, or quickly attacked from behind before it has a chance to turn its spring around.
Unlike the Crushstacean, the Banpyura never shoots its spring toward a player. It also does not stop walking when a player is nearby.
Adding the Ambush flag will reverse the direction it starts to patrol in, going left then right, instead of right then left. In UDMF, Argument 1 lets you set this to Right or Left.
