Yes...

In a way.  It was always a habit to plant only members of the cactus or
succulent families of plants in shells as they like the calcium (alkaline)
content that other plants don't like.  Bromeliads ("air plants") can also be
place into shells as they get their nourishment though other means than the
roots which are used mainly to anchor the plant.  The bottom line is if you
really want to use a shell as a planter, choose plants that like an alkaline
soil content.

Happy Shelling

Richard