亼 ('to gather', an old form of 集) is archaic and not used independently in modern Chinese. It is the inverted 'mouth / converging' top seen in 合 (to join), 今 (now), 舍 (hut / to give up), and 命 (life / order).
memory
An inverted 口 — three strokes coming to a point from above, like things drawing together. That is the 'assemble' idea in 亼.
Components
ideograph
亼jí
to gather; converge
Three strokes meeting at a top point, an abstract symbol of things converging. A pure ideograph, not decomposable into smaller parts in 亼.
Filed under radical 人 (rén, #9) by convention. 人 is not a separate component in 亼, so no strokes are highlighted.
