There is a small protruding lip just over the mouth. When the worm is foraging this lip will be stretching out for sensing food. Worms have no teeth for chewing their food. They grind their food in their gizzard by muscle action. Worms can only take a small particle of soft moistened food in their mouth.
Worms have a muscular gizzard.
Small parts of food mixed with some grinding material such as sand, topsoil, or limestone is ingested. Worms need gaseous oxygen from the air. A constant supply of fresh air is needed by the worms. Worm compost can be used like any other compost. Sterilizing is not necessary.