Bonaire's salt pier is one of my favorite dive sites in the world. The pier is used as a loading dock for ships exporting salt from the island. It's comprised of a series of platforms, each with columns descending to the ocean floor. Each column is overgrown with life including coral, algae, and sponges, creating a beautiful artificial reef. The angle at which sunlight pierces through the gaps in the columns creates some great photography opportunities. At the salt pier, divers can find anything from barracudas to massive schools of fish to frogfish. The reef itself isn't in top shape due to the heavy boat traffic, but the lack of coral cover is made up for by the sheer diversity of fauna that this site harbors.
Sponges are super diverse and come in all shapes, colors, and sizes. Contrary to their appearance, sponges are actually animals. They filter nutrients and plankton from the water to get their food. Sponges are also an important part of marine ecosystems, as they provide food for organisms such as turtles and angelfish, and they provide habitats for fish trying to camouflage.