Coral: Very common in the area of Bikini Bottom. It is possible that this plant has been domesticated, seeing how it can be steamed and eaten, though it is not very tasty. It appears to be foul, seeing how the pioneers struggled surviving on this, heard in "Pizza Delivery," if not something else. It comes in red, yellow, and blue, all with multicolored spots. It is small, and tube-like.
Seaweed: Acts as somewhat, weeds in Bikini Bottom, growing so tall in forests that you need swords to slice your way through, as seen in "Club SpongeBob." It is seen in "Ugh," that you can roast and eat different types of seaweed. it grows tall, and lush in the Kelp Forest. It grows at a minimum of what it would, in Bikini Bottom.
Sea Anemone: Acting as common flowers in Bikini Bottom, they as well have been domesticated for decoration, though smaller species, may have a use for them. They are known to grow beautiful in Bikini Bottom, as well as around the area. They are planted in Squidward's garden.
Kelp: Very Lush, and known to be greatly domesticated in Bikini Bottom. SpongeBob's favorite cereal is made from Kelp. It has grown into a forest on the outskirts of Bikini Bottom. Squidward also has this in his garden, especially in the episode, "Giant Squidward," when he used Kelp Accelerator on his plants.
Sea Flowers: Not much is known about these, except for the fact that SpongeBob grows them around his house.
Sea Palms: Common in Bikini Bottom, especially common in Jellyfish Fields, where they grow throughout the grass.
Barnacles: Nothing is known about them in Bikini Bottom, but it is obvious that they are familiar with them seeing how they are usually personified and used in speech.
Algae: Grows on various rocks, and mountain formations.