wrote in message
...
I have a fridge\freezer with an ice maker. The automatic ice maker
storage got high and a single ice cube got
placed behind the large storage tray, it has sat there for a while,
but started getting smaller, now it is
almost nothing.

What causes this cube to get smaller in an environment that appears to
stay the same?

Sublimation. Evaporation from the dryer air around it. Happens to snow also.