Humungous fungus: A challenge to what a life form is exactly
A 9.65 square kilometre fungus (the size of 1600 football fields) is apparently a single individual:
The world's biggest fungus, discovered in Oregon's Blue Mountains in 2001, is challenging traditional notions of what constitutes an individual. The underground fungus--estimated to be between 2000 and 8500 years old--is also deepening our understanding of the ecosystem, ...
Of course, if the tree-killing Armillaria fungus were not a single individual, how would it know? Here's more on the fungus among us.
The discovery lets humans off the hook for perpetuating Armillaria. This one did quite well without any human input, as far as we know.