Here we have a head with a lid in it, near the top. Imagine the top of someone's head being closed by a lid. Open that lid up and peer inside... it's full of yen coins, the currency of Japan. Jackpot! And all those yen coins have a nice round shape, naturally.

What does the word yen sound like? It sounds like えん. Why? because back in the day, Japanese used to have a "ye" sound, but now it doesn't. Instead, it's an "e" sound, which is why yen = えん!