Several parts combine into one character.

貝 is a picture of a cowrie shell — the top is the shell, the two legs below are the protruding foot or the shell's markings. In ancient China this small, hard shell was money. As a result, almost every character containing 貝 has to do with money, wealth, or trade.

The simplified form is greatly reduced to 贝 — because it serves so often as a radical, the simplification pays off heavily.

Look at the characters built with 貝 and you see the ancient economy: 財 (cái, wealth), 買 (mǎi, buy), 賣 (mài, sell), 貴 (guì, expensive), 貧 (pín, poor), 貯 (zhù, store up), 販 (fàn, to peddle), 購 (gòu, to purchase) — all start from shell-money.

Korean hanja-sound "pae": 貝物 (paemul, jewelry / valuables), 魚貝類 (eopaeryu, fish and shellfish), 貝塚 (paechong, a shell-mound archaeological site). Mandarin: bèi, 4th tone. 贝壳 (bèiké, seashell), 宝贝 (bǎobèi, treasure / darling), 扇贝 (shànbèi, scallop). Japanese: on-reading バイ (bai), kun かい (kai). 貝 (kai, shellfish), 貝殻 (kaigara, seashell); it appears in Japanese surnames too.

Memory aid: a shell on top, two legs below — long ago, this was money.