A skin delimits insides and outsides, and sets a reference point for something to be distinguished form everything else. The world we live in has a skin—a bubble skin—made of gas. But it isn't what it's made of what matters, not even what it does (it enables our living); what matters the most about our world's bubble skin is its meaning.
It gives life a meaning. Not life as a biological phenomenon, but life as a metaphor of movement and will. What is alive, after all? Something moving at its own will, in an independent fashion. But, is there really something that depends only on its own? Although there might be several degrees of freedom, I think nothing can absolutely depend on its own, I think that everything we know depends on interaction.
It would be a nonsensical argument to say that our world is outside and our universe—everything but our world—is inside; a small, perhaps insignificant, outside, and a big, perhaps infinite, inside. It makes sense, nevertheless, to say that we can enter the universe if we get through our bubble skin, that the skin of our universe as we know it is our bubble skin. It would also make sense to say that we could enter the real world if we could only get through our human skin, but we can't, so it doesn't make sense.
We can't, then, get outside our skin—not as a complete, willing being, anyway. Still, some things inside us whose will, even if unknown, may exist, are able to travel inside and outside the human skin. Those things make possible for different worlds to interact; after all, everything in this universe with a skin (maybe this universe itself) is a world on its own.
Life is an spectacular phenomenon that happens among an infinite number of scales. In the same sense that sounds, actions, odors, and the like travel form one human to another to make social interaction possible; we, as humans, are looking for our world to interact with other worlds inside this big, perhaps infinite, universe.
And so it happens that our cells, through their bubble skin, make life possible. And so it happens that humans, through their human skin, give life a meaning. And so it happens that our world, through its bubble skin, makes it possible for life to be a meaningful metaphor.