What is this?

[Blob101]

Can someone help me know if these white things are harmful or not and what are they. They just suddenly appeared on the tank. They move and close when touched and are sensitive to other movements. They appear on shells, rocks, and even on plants. Thank you.

 

[vetteguy53081]

Sea bunny as stated in other thread you have
Can be toxic and are short lived

 

[kmanuele]

Jealous, that's super cool