Green masses in ditches and ponds are often caused by networks of long threads originating from filamentous algae.

Sand can look beautiful under the microscope. Of course there are many different types of sand and so far I have only studied a few types with the microscope.

Diatoms are brown microalgae that can be found in all freshwater and marine environments. They are an important link in the ecological cycle. In streams and rivers you often see stones covered with a brown layer that is formed by diatoms.