  The Casimir effect is a macroscopic evidence of the quantum nature of the
vacuum. On a ring, it leads to a finite size correction to the vacuum energy.
In this work, we show that this vacuum's energy and pressure acquire
additional, sizable corrections, when the ring's radius is increased fast
enough, an experimentally accessible model of an expanding universe. This
effect is distinct from the dynamical Casimir effect: it is a manifestation of
the conformal anomaly, originating from the spacetime curvature induced by the
increase of the ring's radius. This anomalous dynamical Casimir effect is
measurable through the work necessary to increase the ring size, which becomes
non-monotonous in time.
