Ammonoids are found in rock layers from six different geologic periods yet ammonoids are considered excellent index fossils explain why this is possible

Ammonoidia is a phylum (maybe subphylum I don't remember exactly) and includes a great number of individual species which can each be tied to specific geologic time periods. Due to their calcitic and aragonitic shells they hold excellent preservation potential and are commonly found.

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.