Matryoshka dolls (Russia) and Story within a story (Humanity)

aka. Russian stacking doll, nesting doll, Russian doll.

It is a set of wooden dolls of decreasing size placed one inside another.

What is interesting is that nested narratives (like 1001 Arabian Nights) are also called Matryoshka stories. The connotation has also expanded in recent years to find technological connotations: Matryoshka Representation Learning in AI, Matryoshka Brain in futuristic structures, Matryoshka Video Format in Video Technology, amongst others.

Etymologically, Matryoshka is a diminutive (conveys that something is small) form of Matryosha (Матрёша), in turn a hypocorism (pet name) of the Russian female first name Matryona (Матрёна), which is taken from the Latin root Mater, meaning mother. So Matryoshka, a common 19th century Russian peasantry name, conveys "Little Mother".