Smooth Bubble Algae

Description:
Bubble algae is pretty easy to recognize.  As can be seen to the right, bubble algae forms green bubbles on a hard surface like live rock.  The bubbles can be masses of small irregular bubbles, or can be single or small groups of larger rounded bubbles up to over an inch in diameter.  The surface of the bubble can be smooth or rough depending on the particular species.

Good or Bad?:
Bubble algae is BAD.  After the initial excitement of finding cool looking green pearls in your tank, you should remove the bubbles to keep it in check.  Bubble algae grows rapidly and can spread through the tank.  It will tend to crowd desirable specimens out.  Fortunately, it is normally possible to manually extract bubble algae and keep it under control unlike hair algae.

Notes: 
Bubble algae can be picked off by hand.  It is unclear if breaking the bubbles can help spread the pest or not, but should probably be avoided.  On small rocks, it is sometimes easier to remove the rock in order to pick off the pests.

Some types of Mithrax crabs are reputed to eat Bubble algae, but the jury is still out on that one.  While I have observed them eating bubble algae, they do not appear to be a complete method of control.  There is also evidence that Red Sea Sailfin or Naso tangs may eat the stuff.