The ‘Matryomin,’ a novel instrument consisting of a theremin housed inside of a matryoshka, was used in a performance of a Beethoven classic
that took place in Tokyo ten years ago. There were 167 musicians involved in the performance. It goes without saying that a matryoshka

is one of those Russian nested dolls in which wooden dolls of progressively smaller sizes are nested one inside the other.
Regarding the theremin, it is an electronic musical instrument that dates back to the early 20th century and does not require any interaction from the musician.

In the old video that may be found below, its creator, Leon Theremin, demonstrates how to use the instrument.
In addition, if you follow this link, you’ll be able to watch the Matryomin Ensemble play an entrancing rendition of ‘Amazing Grace.’ Have fun.