The first evidence of multicellularity is from cyanobacteria-like organisms that lived 3–3.5 billion years ago.
how they survive
The cell proliferates to produce many more cells that result in the multicellular organism. The process starts with a single fertilized cell that increasingly divides to form many more cells. In the process, the genome causes the cells specialize through selective gene expression.
Below 50 meters, the ice now behaves in a ductile manner rather than a brittle manner, meaning it will stretch and fold under stress rather than fracturing.