Synedra
Diatoms reproduce asexually by forming two new valves inside the parent frustule. The contents of the cell divide and separate so that the protoplast of each new cell is now enclosed within one old valve and one new valve. One of the new cells will be the same size as the original cell, while the other will be slightly smaller. As a result of these divisions the valve size within a given population gradually decreases. Rarely, sexual reproduction occurs and produces a larger valve.
	Note the newly-formed valves running lengthwise along the center of this cell. Once these new valves are completely formed, the components will separate into two new cells.