Collagen despite what the cosmetics companies say will not go into the skin, the molecules are too big to go through the skin surface. As you said. Pro Collagen Marine Cream is actually made from a seaweed, collagen is usually from cows. Yes so your are putting dead cows on your face, if can also be obtained from humans. Doubt the companies would use this one, buy hey you never know. So what PCMC does is support your collagen level, the company Elemis does not say it is a collagen.
There was an article in the Daily Mail about collagen and false claims, they showed a photo of Elemis and then had to remove it due to the fact PCMC is not actually the collagen ingredient they were talking about.
This link gives the full ingredients for PCMC and a bit about it.http://www.bestantiwrinklecreamrevie...eam-review.php
It was the first link that came up so I just used it.