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Re: Hydra like things...

     >They are light yellow/green in color.  They seem to grow on a shared
     >stalk like some marine polyps, and one little guy is at each node.  
     >Size is about <1/4" tall.  The shared stalk is about the size of a 
     >human hair (though a little smaller).  I can definitely see their 
     >little arms when they are in the water.  I've yanked them out, but 
     >saved them (as I'm not quite sure if I want them or not).
     Hydras are solitary, not colonial, as you already know, but there are 
     freshwater colonial polyps.  The genus found in North America and 
     Europe is Cordylophora.  I suppose it could also be a bryozoan, as 
     some can resemble polyps.  Bryozoans are far more common than 
     freshwater polyps.  A good reference on this topic is "Freshwater 
     Invertebrates of the United States", by Robert W. Pennak.
     They shouldn't harm your fish or plants, but bryozoan colonies can get 
     pretty large (some can cover several square feet).  I suppose a 
     heavily planted tank can produce enough detritus, algae, protozoans, 
     etc. to support a large bryozoan colony.  Freshwater polyps rarely 
     exceed 100 mm in length.
     Nothing to worry about, but plenty to marvel at.
     Kind regards,