What are the ‘fireworks’ or fuzzy patterns we see when our eyes are closed, and how/why do they appear?

Question: What are the 'fireworks' or fuzzy patterns we see when our eyes are closed, and how/why do they appear?
- Keywords:
  'fireworks',
  closed eye
Asked by to Andrew, Emma, Michael, Nancy on 25 Jun 2014. This question was also asked by .
- Michael Kelly answered on 25 Jun 2014:
  
  They are caused by mechanical stimulation of the eye. The retina can only code information as light so if the retina gets squeezed or nudged you see light patterns. Not really a good idea to do this too often squeezing the eye reduces the circulation in the retina and could damage it permanently.

Question: What are the 'fireworks' or fuzzy patterns we see when our eyes are closed, and how/why do they appear?