So......these little guys turned up overnight. Basically they look like miniature jellyfish and the closest ID I could come up with was a hydroid jellyfish; however mine do not crawl along the glass, they have the classic jellyfish swimming style. They like light and are up at the top of the water.

Here is a link to pics: http://picasaweb.google.com/zcatzmeow/StrangeCritters


Sorry for the pic quality, my camera and I have difficulty understanding each other