I've kept two. The first was 100% bleached when I bought it (noob mistake) and barely survived for months. Research indicated that the presence of another member of the same species might facilitate zooanthellae recolonization so I bought a second. It was injured and didn't survive, but the other did start browning up again almost immediately.
Unfortunately it didn't survive moving into my new apartment. Was just too cold outside.
Anyway, both moved constantly for a day or two. The one I had longest would move a few inches every couple of weeks but didn't go far from its favorite spot. In nature they stick their foot down a crevice so they can retreat if threatened. If lighting and flow are good, it will find a place it likes and usually stay there or at least close to it.
Someone stop me! Please! But... not just yet...
55 Gal Tropical FW
55 Gal Mixed Reef