I inherited a neglected tank (30 gal) saltwater. I have since been able to revive it and am starting to see some things growing that I can not identify. I've put a couple of pictures here so maybe someone can help.
You are asking about the yellow ball in the upper picture? It is a sponge. Those reddish-brown polyps surrounding it are Protopalythoa sp. - maybe. One is always supposed to be tentative these days with soft coral identifications.
The lower picture appears to be an Aiptasia anemone.
With the aipstasia (and the only reason I was unsure about this is that most seem to have a brownish color this one is white or translucent) I should get rid of (I just wanted to make sure before I did something about it).
THe sponge... Beneficial or Neutral? (If so what can I do to take care of it?) Harmful (If so what can I do to get rid of it?)
Aiptasia will look clear or colorless when they are not packed with zooxanthellae. They are not harmful when there are only a few. But they are powerful stingers and can sometimes multiply uncontrollably. I have mixed feelings about telling someone to kill a lone Aiptasia in an aquarium. They are beautiful and relatively harmless in small numbers.
The sponges are often considered beneficial for their filtration capabilities. I would suggest you leave it and do nothing special for its care. Don't place it in very bright light.
