I've never seen anemones like quadracolor and magnifica travel through the sand. Condylactis, I wouldn't put it past them, if the sand is shallow enough for them to reach the bottom glass with their foot and the conditions where they are, are simply horrible. They typically keep their foot concealed in a hole anyway. If a healthy mag or BTA were placed on an isolated rock island, I don't believe they would leave. At least I've never seen it happen. Maybe I could see it happening, if they simply could not survive the conditions on the island. In witch case they would most likely detach from the rock and drift away before trying to move through the sand. I don't keep quadracolor very often, but I've always had success with keeping magnifica and Condylactis isolated by using a rock island.