Hallo, what is this?

[Fares Awiga]

Hello.
I recently started my first salt water tank (around 90 Liters) and cycled it for around 6 weeks
I started with a some dry rocks and a couple of live rock from my LFS to kick start the cycle.
yesterday I bought my first 2 Corals and a clean up crew consisting of 4 Red legs hermit crabs and 3 turbo snails.
i noticed something on my Zoanthus
Is this something I need to worry about?

thanks a lot!

 

[KJ]

Welcome to R2R!!! Look like sponge.