Any idea what this whire threaded thing is

[Markdickenschwanz]

Have these growing in the inside of my overflows. Some type of algae ? Should I be worried ?

 

[vetteguy53081]

Have these growing in the inside of my overflows. Some type of algae ? Should I be worried ?

These are pineapple sponge and favor dark areas with low flow and emerge from silicates in the water and making them short lived