I searched a couple of very good tropical fish places near me and found these gems. A Triumphal arch and a Pharaonic giant head. All I have done is add the same colour dust effect to tie them into my base boards. These will make excellent centre pieces, emerging from the sands.
To create the dust effect I use chalky pastels, scrapped into my mixing palette with a scalpel. I use tan, white, sulphur yellow and red and mix it a generous slug of acrylic thinners. Exact proportions are not my strong point. I keep mixing pigment till it looks about right, and I keep splashing liquid till I get something like a milk consistency, making sure to not mix too perfectly as slightly varying tones looks better. As it dries out it deposits and reveals the powder again, incredibly fine, just like wind blown dust. When dry I matt spray seal it. This both holds it in place and takes any lingering shine off the surface.