Like the idea of cover in the tank especially root systems where the rays can swim beneath,looks nice but the problem with this kind of hollow ornament is that they create dead spots within them where the water doesnt circulate,im sure many people on here can relate to what im saying,when removed from the water after a few weeks there is a terrible smell that builds up inside this type of decor,drill a few holes in it where you can't see them then feed some sort of air line or outlet from a filter to keep the water flowing through.
Nice Rays!