Anyone Know What Works Best on Sea Shells and Sea Stars?

Okay, Crafty bloggers...I need your help...

What works best for decorating sea shells and sea stars?

Paint?
Spray Paint?
Glitter Glue?
Spray adhesive with a dusting of glitter?
This year, we are doing a sea theme for Christmas...we are making Christmas ornaments out of sea shells...I am thinking of either painting them or else spraying them with glue adhesive and then, dusting them with pearly glitter so that there will be some consistency.

Has anyone ever painted shells?

How about sea stars?

What kind of paint did you use for such a project?

How about spray adhesive and then, glitter?

I want it to be something that my sons can help make, and that won't be toxic to the kids our dog.

I am worried about what is the best paint vs. what is the safest...when I have used kids' washable paints for projects in the past, they only seem to hold up if you laminate them and obviously, I can't laminate sea shells or sea stars.
Any thoughts, suggestions, etc. will be greatly appreciated.

Also, if you read this and you have a neat idea related to decorating for Christmas with a sea shore theme, I would love to hear from you, too:)