From Sonic Retro
|Game: Sonic Mania|
They hover around a certain point. If the player gets close, they will release six flying orbs that will make a circle around them, drawing a big 3D polygonal shape on the screen. This polygonal shape will eventually get smaller until it becomes the size of the player, causing damage if they are still in contact with it; alternately, the attack will fail if the player gets too far away or destroys the Sentry Bug.