I have,
I've seen creatures similar to this in California tide pools, although admittedly not as creepy looking as this one. My first guess was colonial ascidians, a variety of sea squirts, one of our distant ancestors on the evolutionary tree, and one of the most primitive of chordates., but apparently I wasn't too far off.
http://www.news14.com/content/local_news/triangle/611427/raleigh--sewer-creature--surprises-city-officials/Default.aspx
