If not picked, it will glow at Dusk and Night, providing enough light to ward off Charlie. While glowing it also has a Sanity aura.
The sprout can be permanently destroyed with a hammer for two Limestone and a Brainy Matter if it is not already picked.
Making a base on an island close to a sprout is useful in Monsoon Season, especially when Research Stations get flooded, as the Brainy Matter can be turned into the Brain of Thought, which allows prototyping without the need of a station. It also gives a good sanity bonus (due to the sanity drain from excess Rain).
It is useful to put Brainy Matter in a Bundling Wrap as it prevents it from spoiling.
Their brain shape and the fact that they spawn in the reef biome could be a reference to brain coral (Diploria labyrinthiformis).