Brown slime is a filamentous algae and each strand is just one cell in width. It grows on a solid surface, often on other algae. The threads are very narrow which makes it slimy. We therefore call it brown slime as it really does not have any proper English name.
It is found in all oceans from the Arctic in the north to the Antarctic in the south. However, it is not found in the tropics. It tolerates low salinities quite well and is therefore often found in estuaries and even in fresh water. Very few brown algae are found in fresh waters.
The brown slime is the first algae to have all its genome mapped. This is because of how tough it is and easy to cultivate. It can be grown on a petri disc and reaches full maturity in just 3 months.