Hmmm. I really don't think this is fungus...at least not any kind
I've ever encountered. What kind of fungus are you thinking it could
be?
I agree with Liisa. It sounds like fungus. The kind that grows in aquariums.
g Stringy white stuff, often grows on driftwood.
Is your tank newly set up? IME, fungus is more commonly a problem in new
tanks.
It's not harmful. Some fish may eat it, but it's like a temporary problem. If
your tank is new, just wait, and it will likely go away on its own.
Leigh
http://www.fortunecity.com/lavender/halloween/881/