Strange growth on my clam

Question

clam growth   Hi David,

I have been in the hobby for 20+ years and have never seen this before. My job moved to China recently and of course I started a reef as soon as possible. This tank is about 6 weeks old. In China when you buy a tank it is deliver to your home completely set up as it was in the shop including water and livestock so I got the clam with the tank. The clam is doing great but this thing started to grow on it in the first week and it grows fast. I have no idea what it is or if it poses any treat to the reef. It is some sort of filter feeder and it does not bother the clam, it runs along the side of the clam from the foot to up under the mantel.
Please let me know what it is.
Thanks for your help.

Ed

Answer
Hi Ed:

It's nothing to be alarmed about; it's common for marine invertebrate and other marine organisms to live on the exterior of a clam. These may include sponges, coralline algae, macro algae, marine plants, small corals, and pods, just to name a few. Marine zoologists believe these marine animals/organisms as well as the clam interact with each other (symbiosis) to help feed and protect each other in various ways.

From your image it appears to be a sponge growing on it.

I wish you luck with all your saltwater aquarium endeavors.

Sincerely,
Dave