Spiky thing sticking to snail shell

[JGT]

I heard about barnacles but don't know what exactly they are. Are they like snails?

More in the crab/lobster family.

 

[Subnautica]

More in the crab/lobster family.

I just googled it and they are interesting creatures. Surprised to know they are crab related.

 

[Subnautica]

@JGT @SHNICI Update: I emailed John of reefcleaners and he said that thing is a Thorny Oyster! Interesting!

 

[dhanking]

It does look like a small clam or mussel or oyster, I have many around my tank.

 

[Subnautica]

It does look like a small clam or mussel or oyster, I have many around my tank.

Do they live long in aquaria?

 

[SHNICI]

@JGT @SHNICI Update: I emailed John of reefcleaners and he said that thing is a Thorny Oyster! Interesting!

Thorny (spondylus) oyster , match the one you have, and read about if you wish
Usually after you take them out of the water, if isn't from the Scallop genus it can survive for longer (most of the clams/bivalves/oysters will be fine w/o water for many hours), they close them self and keep the water which is trapped in.