Don't quite know what the snake and skull represent?
Death and decay are what the snake represents and death and mortality are what the skulls represent. The two of them together are most likely about the amount of time that each of us has left on earth, and how we need to live each day to the fullest. To be honest I did not know what the two of them meant either, so I searched it and this is what I come up with. It doesn't necessarily  represent the dark side, (to some it does) but you can wear this unique tattoo print on a custom made scrub top from us and be reminded of your life left on earth, and how you want to live it and appreciate what you have.