The spots are called Sporangiia, they are sacks that contain the spores
that
ferns use to propagate. The spores themselves are usually microscopic (or
very nearly so). The Sporangiia will open and release spores, when the
spores land on a suitable surface they will begin to grow into a small
(usually heart shaped) plant called a Prothallia, after a bit the
prothallia
will develop into an adult fern... Or at least that is how it works with
most ferns, there are exceptions, and I don't know the particulars of
aquatic plants.

These growths are nothing to worry about, most of the spores will not
survive, in fact most of them will go into your filter =p. Of those that
do
reach the prothallia stage, only a few will become adults.


Hope this helps

--donovan

That is perfect! Thanks for the help!
Scott Nichting