My questions

Hi. First of all sorry for my English its not my main. Just seen the movie and it was awesome!!!!))) Wanted to ask you few thing i did not understand in the movie: 1.What were the Engenirs running from? were those the little worms becoming "snakes" and then maybe something bigger or infecting other Engenirs like the red head guy? 2.How did "Aliens" allready were exciting? There was a painting on the wall of an alien but how? If to create an Alien you need a human? First the stuff from the urn, then sex, then giving birth to some tenticales creature, then tenticale creture having....something with engenire....an alien comes out. Is it possiable they used humans for a long time before,using that cycle to create aliens on the other LV planet? or maybe there were left other jockeys in the spacecraft that then took the alien to the other LV and that alien was the mother of aliens and started reproducing the eggs? Hope i wrote it good enough for you to understand)) by the way leave your questions or maybe answears to other questions that i have missed. P.S The only thing i didnt like in the movie is the ending,Shaw leaving with David to the planet of origin of the Engenirs. thats just too much. Ohhh.... why did they leave an invetation to us? or it wasnt one?