Hide-and-go-swim: How long was your fish "missing" before it reappeared in your tank?

[PotatoPig]

In perhaps a more unusual case:

I have recently had a coral go missing.

I had a War Coral approximately the size of a golf ball that has disappeared without a trace. My suspicion is that my engineer goby buried it, but from an investigation of the sand around where it was last seen it doesn’t appear to be in the vicinity…