Honestly though, it does not look very "reefy". How about something that is really meant to be in a saltwater tank? I have put some artificial sponges in my reef that look quite real and understanding how difficult it is to maintain non-photosynthetic sponges (nearly impossible) in a reef, I went with artificial ones from here:
http://www.oceanaquaria.com/Corals.php
and here is a pic of my tank with the artificial sponges in it, as the oranges sponges:
