They have many unique characteristics which separate them from the eubacteria. They have distinctive membranes, unusual cell walls, and unique metabolic systems. Many archaebacteria live in anaerobic conditions rich in carbon dioxide and hydrogen. Eubacteria Eubacteria is the most widely distributed group of organisms. One gram of soil may contain over a billion bacteria.
Bacteria can have three distinctive shapes.
There are coccus which is spherical, bacillus which is rod-shaped, or Spirillum which is a spiral. Gram staining is a procedure that is used to classify bacteria by their cell wall. They are died purple, but only gram-positive bacteria, which have thick cell walls, retain the dye.