Extend Elgg Search?

Can someone explain how Elgg search works (just a brief explanation)?  I don't think there is a crawler with an index used to return search queries.

Is it possible to extend the search functionality?  For example, my profile information won't show up in search, but we want it to.  If I search for a company name and that name is in my email address then I'd like to be able to return that in a search query.  Maybe integrating a 3rd party crawler/indexer and search would be the way to go?  Not sure... just posing the question!

Would this be an easy task?