Mystery Guest Revealed

Thanks to my friend Jason's hard work and research we now have a name for our mystery lake guest.

Bryozoa
The Bryozoa, also known as Ectoprocta or commonly as moss animals, are a phylum of aquatic invertebrate animals. Typically about 0.5 millimetres (0.020 in) long, they are filter feeders that sieve food particles out of the water using a retractable lophophore, a "crown" of tentacles lined with cilia. Most marine species live in tropical waters, but a few occur in oceanic trenches, and others are found in polar waters. One class lives only in a variety of freshwater environments, and a few members of a mostly marine class prefer brackish water. Over 4,000 living species are known. One genus is solitary and the rest colonial.

Thanks, Jason for figuring this out. i was really hoping for "lake monster egg," but this is pretty cool too.

To find out more about bryozoa check out the Wikipedia entry for Bryozoa.
(i know that wikipedia isn't always the most accurate place to get info on the web, but the International Bryozoology Association recommends this page, so...)