Strombus costatus or Conch Shell
16 x 12". $350.
This to me is one of the most beautiful shells and is common in the Bahamas 
where they are caught and eaten (conch fritters and conch chowder) 
and they are becoming less common due to that.
I found this one on a pile of castaways and took it home for my collection. 
The small shell box is mine and containst other small shells. 
The colors are pink and cream ranging from dark to light.