Okay, here's my favorite "shell"-related poetry:

With Sincerest Regrets

Like a white snail the toilet slides into the living room, demanding to
be loved.
It is impossible, and we tender our sincerest regrets.
In the book of heart there is no mention made of plumbing.
And though we have spent our intimacy many times with you,
you belong to an unfortunate reference, which we would rather not
embrace....
The toilet slides out of the living room like a white snail, flushing
with grief....


                             --Russell Edson