Should an egg float or sink?

I'm curious, could you enlighten me on the science behind the question "Should an egg float or sink?" I understand that the buoyancy of an object is determined by its density relative to the liquid it's submerged in, but I'm not sure how that applies to an egg. Does the freshness of the egg play a role? What about the temperature of the water? Could you explain the physics behind this phenomenon in a way that's easy to understand?