empty shell; empty husk
Refers to the empty outer casing left after the contents have been removed, such as an eggshell, nut shell, or insect exoskeleton.
I threw the empty eggshell into the trash.
セミの空き殻が木に残っていた。
An empty cicada shell was left on the tree.
Compound of 空き (empty) and 殻 (shell).