Melt semi-sweet chocolate pieces on top of a double-boiler over hot water. Remove from heat; stir in prunes and coarsely chopped peanuts until fruit and nuts are well coated.
Sprinkle coconut and finely chopped peanuts on separate sheets of wax paper. Drop half of prune mixture, a teaspoon at a time, onto coconut. Roll into balls.
Place in a single layer on a cookie sheet. Repeat with remaining prune mixture, rolling in peanuts. Chill all until firm.