Collections of highly specialized cells are found in multicellular organisms. For instance, in animals, there can be found many types of specialized cells, such as skin cells or nerve cells.
The structure of a cell is related to cell's function. For example, the structure of nerve cells consists of cell body and longer and shorter attachments, called axons and dendrites. The longer attachment, axon, has the function of conducting the nerve impulses, while, the shorter attachments, dendrites, have the function of receiving nerve impulses.
Other example is represented by sensory cells, whose structure and shape are uncommon, being different from the rest of the animal cells. For instance, rod cells in retina consist of numerous disks that possess pigments that are light sensitive. The light received by these pigments represents a trigger for the nerve cells found in the eye to send impulses to the brain.