Golden colonial algae

The term colonial as used here applies to algae composed of free-swimming look alike unicells, which form groups that may be large and elaborately interconnected as in Volvox, or smaller and relatively simple as in Synura.

The Synura colonies shown in this video - taken in phase contrast - have ovoid golden-brown cells characteristic of the Chrysophyta, each cell bearing two flagella whose beating propels the colony through the water with a smooth rolling motion.
The individual cells divide longitudinally, and the colonies also divide into two as they grow larger.

Synura sp. is present as common phytoplankton in lakes and ponds.