Frozen water (ice) has less density than liquid water. How does this propertt of water affect life on earth?

Forzen water or ice has less density than liquid water and this is the reason why ice floats in water and does not sink beneath it. It is a fact that life began under water, and if ice would have sunk then the bootm of the oceans would have frozen. So there would have been no chance of the birth of any living organism. Thermophilies lives deep under the ocean and they survive on the heat from the volcanic vents rather than sunlight. These animals would have did if the ocean floor would have frozen.