b) when asking what it was the answer was somehow not satisfactory (it sounded like it was some waste material from the production of other food)
Yes it is. Its left over yeast from brewing. What, you don't like recycling, or you don't like beer?

The Australian stuff is vegemite, its not exactly the same but it will do in a pinch.

More facts for marmite fans: http://www.guardian.co.uk/g2/story/0...627368,00.html