I have 2 kinds of xenia, 1 green star polyp, 1 leather finger coral, 8 colt corals, and 1 mushroom. All seem to be doing great but the xenia. For months my one xenia would fully open and the stalks were nice and plump. Now it seems most of the stalks on one of bunches is always looking shrunk and wrinkly, but the arms still kind of reach out. They are not melting. They just don't look as full as they once did. One stalk shrinks then gets healthy looking again and back and forth. My other pulsating xenia has 4 stalks. All looked great until a couple of weeks ago. One of them shrunk to a quarter of the size of the others. It still extends its arms but it is just shrunk. Everything else is doing great. Any ideas?