A friend pointed out that "sesamoid" comes from "sesame seed." It refers to the "small modular bones or cartilages that develop in a tendon or in the capsule of a joint." The bones resemble sesame seeds. Then I remembered that the "patella" (the bone on the knee) comes from the Latin word that means "pan," again because of how it is shaped. Is this food-related etymology of bones common? If so, I wonder why?

I had doctors that always used foods to describe the sizes of things (most recently of fibroid tumors). "This is the size of an egg, this is the size of a grapefruit." Maybe because foods are at least commonly known?

Yes, so have I, though, to be fair, I have also heard "the size of a golf ball" or "the size of a baseball."

Lots of medical jargon gets "translated" into English as food-terminology. If you have cirrhosis the pathologist will report your "nutmeg liver," and if you get an amebic abscess it is "anchovy-paste." And on and on ad nauseam (maybe literally!). My guess it that it's a instance of "Groucho's Law" - a common everyday object, found around the house. A.K.A. "Say the secret woid and win a hunnert dollahs!"