A rhino, when compared to a rock of the same size, is generally less dense due to its composition primarily of water and air, resulting in an approximate density of 1000 kg/m^3. In contrast, most rocks, including glacial deposits, typically have a density of at least 1.5 to 2 times that of water. This means that a rock would be significantly heavier than a rhino of equivalent size. The discussion highlights that the density of living organisms is influenced by their water content and air-filled cavities. Ultimately, the consensus is that the rock is denser and heavier than a rhino.