Travis is right, put anything next to a Xenia and it will move to it. Be it rubble, a larger rock, old clam shell, whatever. I had one too close to the glass and I now have 4 stalks on the window. I literally have so much it is time to do something about it. This stuff grows and grows and grows.... I recently aquired some red sea xenia and it too is growing. besides this is the easiest way to propagate xenia.