We will show that a non-collapsed complete ancient solution in $R^3$ is a bowl solition, in succession to Brendle's talk about the rotational symmetry at the Fields Institute last fall. Since the bowl soliton translates with constant speed, we will find several monotonicities of the solution arising from the constant speed. The monotonicities will be established by Harnack inequality and infinite barriers rather than integral quantities, because the solutions are non-compact.