The best description of how the structure of ice benefits the organisms living in the water below is that ice is less dense than liquid water, so it floats on the surface and forms an insulating barrier. This barrier protects the water underneath from freezing solid by insulating it from the colder air temperatures above, allowing aquatic life to survive in the liquid water beneath the ice during cold conditions

. Additionally, the porous structure of sea ice contains brine channels that provide habitat and nutrients for algae and microorganisms, which form the base of the polar marine food web. These algae and microorganisms support a diverse ecosystem of invertebrates, fish, and larger animals living below and within the ice, making the ice structure critical for sustaining life in polar waters

. In summary, the floating ice layer insulates the water below, preventing it from freezing solid, and its porous structure supports a rich ecosystem essential for aquatic organisms' survival.