What is this little green morsel?

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I've recently noticed something odd growing in my fissidens, it's much brighter green and not really mossy looking at all. It's also kind of tough and gangly feeling, not like the moss at all.
I don't remember seeing it when doing a water change last week but a couple days ago it seemed to just jump out at me and say "here I am" so it's got me kind of puzzled to say the least.

Here's a pic, hopefully you can see what it is well enough to make an ID, if not I can try to get a bit better close focus with the ol lady's dslr. I'm asking about the bright green ball in the middle of the shot, the bushy stuff on the left doesn't bother me You can see some of the darker fissidens fronds tangled up in it towards the bottom of the photo.

[catwat]

Riccia fluitans

http://www.plantedtank.net/forums/my...iccia_fluitans

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Great, thanks for the ID.