Vlad I see a case for mobilphone, but the tube seems to have no lenses if having, could be a camera ocular extender or a part of a hand made microscope? It has caracteristics of being a home made part It seems to have two dents in the smaller border. LP
The tube does have 2 lenses, it came in this case, which has some kind of wrench attached to the outside with a snap button. It is too small to be a lens extender, it came with Zenit E and has a diameter of maybe 2cm...
Acording to photos, these lenses have a very small enlarging power. Did you try to see through it putting it over the camera ocular? Perhaps a more confortable observer point of view when using camara on reproduction work. LP