What material that you’ve come across do you think has the most interesting properties?

Question: What material that you've come across do you think has the most interesting properties?
- Keywords:
  material,
  preference
Asked by Vicki to Zoe, Aaron, David, Elaine, Sarah on 11 Nov 2014. This question was also asked by charlottem.
- Zoe Roberts answered on 11 Nov 2014:
  
  Ferromagnetic liquids!
- David Foley answered on 11 Nov 2014:
  
  Chemiluminescence (see my page for an example)!
- Sarah Ashwood answered on 12 Nov 2014:
  
  I feel like being based in Manchester I have to say graphene (we’ve had a new building built here with the sole intent on research into Graphene science). It’s a really interesting material as the structure it has gives it a variety of properties (electronic, mechanical, optical) associated with a metal but it is an entirely organic carbon structure.

Question: What material that you've come across do you think has the most interesting properties?