Nassarius snail question

[chiqui bb]

I purchased 6 small nassarius snails initially and just purchased 6 more but they are much bigger. The larger ones have something on the top side of their foot that looks like a flap of brown skin. What is this? Is it normal?

 

[reeffreak]

I have no idea what it is called but it is normal.

 

[Bifferwine]

Yeah mind have those flaps too. Whatever they are.

 

[yote]

Mines got em to.Its normal.

 

[beano]

mine have it too so its normal, and gross

 

[chiqui bb]

So, I've been watching my tank with a magnifying glass and I think I know what the flap is for. I notice that when the snail feels threatened (like when the emerald crab takes a pot shot at one of them), they curl up in their shell and the only thing I can see is the flap. I think it is like a shield and used for protection. Unfortunately, this doesn't deter the emerald crab. He hasn't killed any of them yet but does occassionally jab them when they get too close.

Pretty cool! I love my magnifying glass!!!