Cisco - your submersed specie is mature & partially calcified Chara ("kara"); a higher form of aquatic algae - which also attests to very hard-water conditions in your pond.
You can confirm this ID by crushing a handful of the stuff in your hand and then taking a sniff. At that point, if you instinctively throw it on the ground and begin looking for a bar of hand-soap, you can be certain that it is Chara (aka "skunk weed").
