Large intestine mucosa. Coloured scanning electron micrograph (SEM) of the mucosa (lining) of the large intestine (colon) showing a fold in the wall (red projection). Food debris (brown) can also be seen. The many folds of the colon provide a large surface area for absorptive cells to remove water and any remaining nutrients from the already digested food. Goblet cells, also in the mucosa, produce mucus which acts as a lubricant, assisting faecal movement and protecting the wall of the colon from mechanical damage. Magnification unknown.