Disapointed in marvel just making up whatever designs of xenos without any explanations or how they even could happen, but more: we do it because I can, type of thinking.
Facehuggers with centerpid legs, implanting several embryos in any opening....alpha alien, the kerrigan wannabe creature, the tiny starship troopers knock off bugs that crawl inside hosts mouths etc. No explanation where they come from or what they do or wtf they are.
But then again trying to explain it will just show how they disregard alien lore and moving away from the perfect organism thinking to: random mutations and they can become crappy xenos or better xenos by random chances.
