why ufo shape change

The ufo's shape are depend on what kind of species alien life or how many of those bio-entity and how they arrange their position inside this UFO, it is also depend on their flying speed. I do not have information about alien's nut & bolt craft shape change.
The shape of UFO :
http://ufo-spacelife.blogspot.com/2007/09/shape-of-ufo.html

 The second fact for ufo shape change is the bio matter of the ufo, so they have gas-like and flexible body. Then their shape is depended on their moving speed. A sphere ufo could became triangle or boomerang then cylinder looked, when it’s attitude shifted from standstill to start moving then to rapid movement:

Aerodynamic Effects on UFO
http://ufo-spacelife.blogspot.co.nz/2012/09/aerodynamic-effects-on-ufo.html
Mysterious alien red mass
http://ufo-spacelife.blogspot.co.nz/2012/10/mysterious-alien-red-mass.html