A definition of quasi-local energy in a gravitational field based upon its embedding into flat space is discussed. The outcome is not satisfactory from many points of view.
A ghost free massive deformation of unimodular gravity (UG), in the spirit of {em mimetic massive gravity}, is shown to exist. This construction avoids the no-go theorem for a Fierz-Pauli type of mass term in UG by giving up on Lorentz invariance. In
our framework, the mimetic degree of freedom vanishes on-shell.
