Protozoans, along with bacteria and fungi, are important in helping to change detritus into food for plants and small animals. Thus they help to 'recycle' dead plants, dead animals and animal wastes. The detritus helps make up the nutrients of the mud or soil on the bottom of the pond that helps plants grow. Some of the nutrients are dissolved into the water which provides food for the floating plants.
Protozoans reproduce by splitting into two identical daughter cells like bacteria or algae.
Some protozoans also reproduce by budding. In budding, a smaller part of the cell, or bud, develops on the side of the mother cell with a nucleus of its own. The nucleus of the bud comes from the nucleus of the original cell which slits into two parts. The whole mother cell does not split. The bud takes food or nutrients from the main cell.