In 1978, V. Arnold suggested a way to construct an elliptic curve for a circle diffeomorhism $f$ and a complex number $\omega$. Namely, glue the borders of the cylinder $0\le \Im z\le \Im\omega$, $z\in\mathbb C/\mathbb Z$, by $f+\omega$. As $\Im\omega\to0$, does this elliptic curve degenerate? The answer is Yes or No depending on the dynamical properties of circle diffeomorphisms $f+\omega$, $\omega \in \mathbb R$. The limit values of the modulus of this elliptic curve are known as “bubbles.”