According to Ocean World, a coral reef can be home to as many different species and kinds of life as a rainforest -- which is part of why protecting them is so important. But these detailed and dramatic landscapes are threatened by pollution and overfishing, and at their current rate of destruction, we could lose 70 percent of the world's reefs in less than 40 years.
The brain coral's name doesn't exactly make it sound like a pretty specimen of sealife, but these crater corals are popular in aquariums for their looks. Their skeletons create "miniature valleys with separate, pinched walls," which, according to Environmental Graffiti, is what reminds us of our own brains -- but they also come in bright colors from blue and red to pink and green.
Some of these life forms appear more familiar than you'd expect. Take this kelp, that looks like a leafy forest. Nutrient-rich kelp may show up on your beach as torn piles of seaweed, but underwater it has a whole different life: This plant, a type of brown algae, can grow from the surface down as far as 150 feet, where the darkness, still water, and variety of sea life that makes its home feels otherworldly.
Feathery soft corals make up this bouquet of brightly-colored sea life. According to the University of California Museum of Paleontology, soft coral are members of the Octocorallia group, named for their "eightfold radial symmetry," which means they have eight smaller pieces that branch off of each main tube to give the downy appearance.
Despite its misleading name, sun coral are a species that don't require much sunlight at all: They can get the energy they need by feeding on plankton, and therefore make their homes in caves and other dark, underwater spaces, according to coral aquaculture lab Coral Morphologic. They're also the only stony coral that set up permanent digs in the Caribbean after invading the ocean in the ballast of ships coming from the coral's native ocean, the Indo-Pacific.
This emerald-colored sea anemone is a dead ringer for the land-based Anastasia flower, a type of spider chrysanthemum. Like other anemones, these attach themselves to hard surfaces -- like rocks and coral reefs -- to wait for fish that inadvertently swim into the stinging tentacles, according to National Geographic.