What snail makes this?

[Kobooi]

This has grown for the last months on the back wall.
Size is approx. 2 cm.
What snail would this be?

 

[Impala67]

This has grown for the last months on the back wall.
Size is approx. 2 cm.
What snail would this be?

It’s a vermetid snails and a big one at that you do not want these guys in your tank. They can be very invasive and spread a sticky white string out to catch food and if it touches your corals it really aggravates them