There is no doubt in my mind that that some UFOs contain beings that are visiting planet earth, how they are getting here is an entirely different discussion but I also believe that some UFOs are biological in nature. If you consider space to to similar to an ocean that has not been explored than it seems a bit easier to understand.
Richard
Are UFOs biological life forms? Here is evidence from NASA. Life (extremophiles) can survive in almost any environment; why not outer space? This film footage, from NASA, depicts what are commonly called "UFOs", as well as "space junk." However, some of this "junk" displays purposeful behaviors and physical morphology which is often identical to simple life forms on Earth. In this film, comparisons are made between these "UFOs" and simple life forms, and the evidence indicates that some UFOs and "space" junk, appears to be alive.