Elastic Potential Energy of a Strained Body

When a metal wire elongates by hanging a load on it, the gravitational potential energy is decreased and

If a compressed spring is dissolved in acid, what happens to the elastic potential energy of the spring?

When rubber sheets are used in shock absorbers, what happens to the energy of vibration?

When a block of mass $M$ is suspended by a long wire of length $L$, the elastic potential energy stored in the wire is $\frac{1}{2}\times \mathrm{stress}\times \mathrm{strain}\times \mathrm{volume}$. Show that it is equal to $\frac{1}{2}Mgl$, where $l$ is the extension. The loss in gravitational potential energy of the mass-Earth system is $Mgl$. Where does the remaining $\frac{1}{2}Mgl$ energy go?