This is a spectacular specimen of a moss animal or bryozoan called Pectinatella magnifica.  It is a colonial invertebrate (many thousands of minute individuals make a colony), is completely harmless, and is filtering the water in your lake.  These colonies start out very tiny, and get bigger as the summer progresses – kind of like a balloon blowing up.  The gelatin center is inert and non-nutritious, and as far as I know nothing eats it.  The colonial animals are all on the outside surface of the “blob”.  They almost always attach to something firm, such as a pier leg or a submersed tree limb.  They are typical of lakes such as Van Vliet – fairly nutrient rich but of good water quality.  They will disappear completely within a few weeks, and overwinter as tiny specks called statoblasts, and may form again nearby next spring.

Susan Knight

UW Trout Lake Station