(If ufos are real)I think UFOs are circular in shape Because as of circular shape it can get large surface area so it take more space in air. for falling down it have to exert pressure so air can help UFOs to stay in air by using less force and by means of it it can cover far distance by less energy for flighting most of the UFOs have dom\crist like structure and at down it have naroow like structure for taking flight and landing. read more