What sea shell is this?

[ArchieFernandes]

I have this sea shell and I’m just curious about it and I have some questions:

Does this come from an invertebrate or is it just a normal sea shell/ conch

How much is it worth?

Is it rare?

Look at the imagines below.

 

[blaxsun]

She sells seashells by the sea shore... I think it's a conch shell, but no idea if it's valuable at all.