The saturated portion of emollient ingredient squalene, which is a natural component of human skin sebum (oil). It is a wonderfully moisturizing ingredient as well as being a source of replenishing fatty acids and antioxidants.
Note that because it’s highly saturated, squalane is less prone to breaking down in the presence of air than less-saturated squalene.
References for this information:
The Journal of Clinical and Aesthetic Dermatology, June 2014, pages 25-32
Advances in Food and Nutrition Research, Volume 65, 2012, pages 223-233
natural moisturizing factor (NMF)