A question about Prometheus's relation to Alien

I've been a long time lurker and have decided to make a thread regarding something that has been on my mind. I do believe that the the ship we see on LV-426 has been there for quite a while (thousands of years) and that the xenomorphic creature we see in Prometheus is a newer version of the Xeno or something entirely different. My only question with this theory is that when the crew of the Nostromo finds the derelict, the Engineer in Alien is supposedly fossilized and has been there for thousands of years. This makes me wonder how the eggs contained in the cargo hold have survived for such a long time. Would they not decay or decompose over time? Does the blanket that Kane breaks when approaching the eggs have something to do with this? Could it be incubating the eggs or be some type of hyper sleep for the eggs that was never turned off until Kane broke the blanket and sounded the alarm?