Jumping seed

...Three seeds form a cluster, and each seed has two flat surfaces and one round surface on the outside. When heated, the seeds move, so they have long been called jumping seeds or Devil's beans, and are sold as souvenirs with paper on which concentric circles are drawn and various compartments are created. These seeds contain the larvae of a moth called Carcocapsa salitans , which belongs to the Tortricidae family, and when they move around inside, the light beans move swiftly, rolling, and jumping in relation to the seed's round surface and two angular surfaces, which is amusing to watch.

*Some of the terminology that mentions "jumping seed" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…3個が一つの塊をなし，一つの種子は2面が平面で外側の1面は円い。暖めたりするとこの種子が動くので古くからjumping seed,Devil’s beanなどとも呼ばれ，土産物として，紙に同心円を書き，種々の区画をつくったものを添えて売られている。この種子にはハマキガ科のCarcocapsa salitansというガの幼虫が入っていて，中で動くと種子の円い面と角ばった2面との関係で，軽いマメがすいすいと動いたり，転げたり跳ぶように動くのでおもしろがられる。…

※「jumping seed」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報