Thread algae

This is a thred algae which was grown in fish tank.In the second picture the chitin cell wall of the algae can be seen

Freshwater Aquarium I̶n̶s̶e̶c̶t̶ Water Mite

I used a syringe to remove a sample of sand substrate from the bottom of my freshwater aquarium. The splotches of granules around the bug are grains of sand. I saw a total of 3 of them from a total of 3 samples. Anyone have any idea what kind of bug it is? I’m guessing it…