Jason de Caires Taylor& underwater sculpture garden in Cancun. "Constructed out of concrete and steel, and bolted to the ocean substrate, the works here act as artificial reefs that provide & ideal habitat for filter feeding organisms.
Use an old tire to create a small backyard pond. My kids, 3 sons, have been helping with yard work and planting. They keep asking for a pond. I think this is a great DIY project to do outside with them. Looks simple.
DIY Cement Mushrooms: The crown is created by digging a hole in the ground and filling w/ cement, the stem is a two-liter drink bottle w/ top + bottom lopped off. Just in case I ever need a cement mushroom.