The algae you have pictured looks more like a Neomeris annulata to me. I have this in my tank; it is from Hawai'i. It can appear singally, or it may spread in to clumps. You will find the top will be a nice green color with radial hairs, and as the algae grows, the bottoms will look white and appear calcified.
The club algae is a form of valonia (bubble algea) and will still have a single finger-like bubble. Look at the algae in question and see if it is solid with little hairs, or if is a cell-like or hollow-looking entity.
Simsimbalabim, is yours from Hawai'i too (if it is indeed Neomeris sp. ), or do you know where it came from?