What would happen if the ice would not float in the water?
If ice sank, ponds, rivers and such would freeze and the ice would sink to the bottom, exposing more liquid water to be frozen at the surface => the entire pond/lake/river/ocean would freeze solid! If all water was frozen solid, no macroscopic organisms living in the water could survive, which means maybe life would’ve stayed mostly unicellular. Or maybe everything would be like a sponge – capable of re-forming itself after getting stuck in a blender.
