Today I notices a white ball growing on my a liverock in my aquarium. It only appears on the piece that was previously in my sump, should I be concerned?enter image description hereenter image description here

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  • Any chance you can take the rock out of the tank for a better picture? Also, is this a saltwater or freshwater tank?
    – Joanne C
    Oct 14, 2015 at 12:35

1 Answer 1


Hard to tell from the picture, but most likely some sort of sponge or tunicate. They typically grow naturally when there is sufficient food and nutrients and with a few exceptions shouldn't be a problem.

Here's a quick guide to common hitchhikers: http://www.xtalworld.com/Aquarium/hitchfaq.htm

Sponges come in just about any color and shape, the most common are ball and pineapple sponges.

  • Has the bit of the look of: en.wikipedia.org/wiki/Oikopleura_cophocerca
    – Joanne C
    Oct 15, 2015 at 2:35
  • @JohnCavan Do you think this is something I should remove or leave? Oct 15, 2015 at 17:36
  • Looks like pineapple sponges to me. I would leave them. They're filter feeders and unlikely they are going to be a problem.
    – Jestep
    Oct 15, 2015 at 18:13

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