Materials Needed:

• Clam-style sea shells (stuck together if possible!)
  

• Paint
  

• Chenille stem (preferably black)
  

• Wiggle Eyes
  

• Glue
  

• Magnet strip (as long as the shells where they meet)
  

Instructions:

Paint the insides of the shells so they look like colorful butterfly wings. Put a generous amount of glue on the back of the magnet; stick the part of the shells where they are joind together onto the magnet.

Fold the chenille stem in half and twist the half closest to the bend together. Seperate the ends (about 1-inch) to be the antenna. Put a generous amount of glue on the twisted part of the chenille stem and glue it along the edges of the shells where they join together to make the butterfly‘s body.

sources:
http://familycrafts.about.com/cs/seashells/a/blshellbutter.htm