Hi all,
"Mossy" wood in the link looks really good, Even though they are called "moss" balls, they are really a green algae (Cladophora sp.). They don't tend to stay attached very well, unless there is very little current, shrimps love them. I've got some growing on some of my wood, but it never forms a very good carpet, it also collects a lot of sediment so I give it good swirl around in a bucket of tank water every couple of weeks
I got fed up with trying to keep Riccia etc attached, but I found the moss they sell as "Christmas" moss (probably Taxiphyllum montagnei) attaches to everything really strongly (including the aquarium glass) and real Java moss (Taxiphyllum barbieri) isn't far behind.
I've got another moss, which forms the most amazing lush green cushions, like moss balls but on a much bigger scale, which I think is Peacock moss (another unnamed Taxiphyllum sp.), and that also grows on wood, although its not quite as good at staying attached.
Tropica says Xmas moss doesn't grow very well, but that hasn't been my finding and I've given away loads of it (mainly to PP members).
Peacock moss at the top, Xmas moss below
Link here to a good mosses resource:
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http://www.aquamoss.net/Introduction.htm>
cheers Darrel