Growth and creature

Question

Purple growths  

Sponge looking growth   I have a couple of weird growths that I thought might be sponges?? I can not find anything on the internet that really looks like them. My tank has been doing so good. I have a bunch of baby snails and little white star fish. I don't want to take any chances and have some weird growth that will kill everything. Thank u

Answer
Hi Debbie:

Always a pleasure to meet another enthusiast.

No cause for alarm, from the images you've provided this is a harmless species of sponge from the indo-pacific. It typically never gets more then an inch thick and it never bothers anything. It's a filter feeder and unless it's causing visible harm you shouldn't be concerned. They are a welcomed addition to most reef microcosms. It actually will help keep live rock together really well, as it grows around and on the underside of live rock. It will also help stable wobbly rocks in your aqua-scape over time.

Having these sponges grow on your rocks is a sign that you're taking great care of your aquarium and water parameters.

Happy Thanksgiving!