Sponge growing on clam?!?

[fessoclown]

There is a dark purple sponge growing on my clam. It is growing pretty fast and has reached the edge at the mantle. Should I be worried/do anything about it. The mantle still extends and comes out, it is not out in the picture as I moved the clam to get a good picture of it.
https://lh6.googleusercontent.com/-QczEfjLVQIU/VR1DXP73vcI/AAAAAAAACcY/k_31X7l0FSM/w496-h661-no/IMG_20150402_092437.jpg

https://lh6.googleusercontent.com/-Bz19JfvymmA/VR1DUpohThI/AAAAAAAACck/T9mFLt2vk6o/w496-h661-no/IMG_20150402_092459.jpg

Thanks for looking!

[Pife]

That almost looks like cynao to me.

[cloak]

I don't think it's anything to worry about. If you do want to try and get rid of it though, just use a wire brush to remove the sponge from the shell. This should be fairly easy to do. GL.