I made a very big (2.5G/10L) natural saltwater ecosphere. I went to the North Sea and brought seawater and sand with me in jerrycans. Then I built the huge ecosphere and it is full with all different kinds of life. There's a starfish and a crab and even a crab larvae. There's also amphipods and a lot more crustaceans and different kinds of seaweed and marine plants.
Enjoy!

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