What’s the most interesting thing you’ve found at the end of an experiment?

Question: What's the most interesting thing you've found at the end of an experiment?
- Keywords:
  experiment,
  interesting
Asked by anon-181146 to Laurent on 18 Jun 2018.
- Laurent Dupays answered on 18 Jun 2018:
  
  The cardiac conduction system is a group of cells responsible for heart’s beating. Unfortunately, you cannot see, and study, those cells in the mouse heart easily as there are mixed with other cells. Using genetic engineering, we have been able to mark those cells in green and see them clearly. The first time I saw them under the microscope it was quite something 🙂

Question: What's the most interesting thing you've found at the end of an experiment?