A hexahedron (plural: hexahedra) is any polyhedron with six faces. A cube, for example, is a regular hexahedron with all its faces square, and three squares around each vertex. There are seven topologically distinct convex hexahedra, one of which exists in two mirror image forms.
Some bacteria that can help the environment are called decomposers. They are nature's recyclers! They return basic chemicals to the environment for living things to reuse! For example, the leaves of many trees die in the Autumn and drop to the ground.ome bacteria that can help the environment are called decomposers. They are nature's recyclers! They return basic chemicals to the environment for living things to reuse! For example, the leaves of many trees die in the Autumn and drop to the ground.
The cytoplasm and plasma membrane of most bacterial cells are surrounded by a cell wall; further classification of bacteria is based on cell wall characteristics (see Gram's stain).They can also be characterized by their patterns of growth, such as the chains formed by streptococci.Many bacteria, chiefly the bacillus and spirillum forms, are motile, swimming about by whiplike movements of flagella; other bacteria have rigid rodlike protuberances called pili that serve as tethers.ost bacteria are of one of three typical shapesârod-shaped (bacillus), round (coccus, e.g., streptococcus), and spiral (spirillum). An additional group, vibrios, appear as incomplete spirals.