  It is known that scale invariance is broken in the developed hydrodynamic
turbulence due to intermittency, substantiating complexity of turbulent flows.
Here we challenge the concept of broken scale invariance by establishing a
hidden self-similarity in intermittent turbulence. Using a simplified (shell)
model, we derive a nonlinear spatiotemporal scaling symmetry of inviscid
equations, which are reformulated in terms of intrinsic times introduced at
different scales of motion. Numerical analysis persuasively confirms that this
symmetry is restored in a statistical sense within the inertial interval. At
the end, we discuss implications of this result for the Navier-Stokes system.
