Head
If you feed a lot of beans to a geoduck, its head will grow larger. To a geoduck, beans are a brain food, so by eating beans, it can grow an incredibly large head. Geoducks already look strange enough as it is, let alone with engorged heads.
ず, とう
あたま, かしら
None
As the geoduck eats more and more beans its head gets bigger and bigger, until finally the head explodes like an atomic (あたま) bomb. BOOM! Geoduck parts go flying everywhere and pieces of its massive head float to the ground as atomic fallout.