Black Mangrove Seed
Very few true plants can survive in saltwater. The Black Mangrove is one of them. (Although it can survive in freshwater as well) Black mangroves can remove nutrients from your tank that fuel nuisance algae, as well as other contaminants from your tank's water.
Because they do not "go sexual or respire" like macro algae, they present less risk to your systems ph balance, and have become popular recently with many aquarists. With proper trimming the plant can spend years in your refugium, larger plants will need an open top to grow out of, if you plan to grow the tree.
Many people are beginning to add the Black Mangrove to their display tank, as they want to mimic nature as closely as possible, while providing a habitat for their fish who will spend a large portion of time swimming in and out of the tree's roots.
These black mangrove seeds have been sprouted to ensure viability.
We have some articles on mangroves here for your convenience: