Nutshell

Walnut shells can be used for cleaning and polishing, as a filler in dynamite, and as a paint thickening agent.

[1] Their high porosity makes them also ideal in the production of activated carbon by pyrolysis.

The expression further gave rise to the journalistic term nut graph, short for nutshell paragraph.

In Hamlet (Act 2, Scene 2) the title character exclaims: "O God, I could be bounded in a nutshell, and count myself a King of infinite space".

Pliny the Elder mentioned in the encyclopedic Naturalis historia a report by Cicero saying that a handwritten version of the Iliad by Homer would have fit in a nut[shell]: "in nuce inclusam Iliadem Homeri carmen in membrana scriptum tradi