The face that is shown isnt from any aliens ,we have no kind of proof that really tells us that the face piece is by an alien. The piece thatwas spotted was shadowy so it could of been mess with to look like that, instead it could of look clear and smooth but when they touck the face it looked like if there was a shadow .The piece looked if it was during a war Many places that went to go see what the face was made of an airplane,some sent there space robots but they got unclear information .many thought there was life on mars back then so thats hopw the face appear .no one really knows how the face was made. Skeptics thpought the alien marking was covered up by haze so if that was true no one would find out. The face had become popular that it ended up becoming a big hit into hollywood. So no one really klnows how it happen its what ever you believe.