It doesn't waste any time chewing its food. Its tentacles surround a food item and bring it inside its body. A single amoeba can eat thousands of bacteria each day. Amoebas eat so many bacteria that they compete with nematodes for food. Soils with lots of protozoa have fewer nematodes.
Amoebas belong to the soil recycling crew.
They can't use all of the nutrients in the bacteria they eat. So a lot of the nutrients go back into the soil. Plants use these nutrients to grow. Amoebas and other protozoa must breath oxygen. They mostly live in the top layer of soils that mix well with the air.