Where the shape comes from
Two readings have run side by side since antiquity. As an object it is a ladle — the bowl at the top, the handle sweeping down. As a figure it is 人 written backwards, a person who has turned round, and that is the reading that works in 化 "to change", where an upright person and an inverted one stand together, and in 北, two people back to back. 老 and 比 carry it too.
汉字 filed under 匕
No published character on HSK Guide is filed under this radical yet. 汉字库.