[Dentoid]

I have seen them do this with any change in the waters ions. So a shift in Alk, pH, Mg, Ca, temp and/or salinity will cause them to do this if it is big enough. Sometime a water change will make them do this too.

Anemones are like semipermeable membranes. They must equalize the ions inside their cavity with the ions in their environment. Otherwise, they would explode. When their environment changes drastically, they must expel their inside water and replace it with new water to equalize. This is why you hear so many reefers say that a stable tank is needed for anemones.

Have you been making any changes to your tanks water chemistry? Any additives? Any changes taking place in pH, temperature or changes in salt type?