Accoutrements Glow In The Dark 4" Jellyfish Holiday Ornament This 4" (10.2 cm) tall soft vinyl ornament is just as good on a Christmas tree as a rear view mirror. Put a bunch on your tree and when the lights go out, these glow-in-the-dark wonders will turn it into an undersea wonderland. Use year-round in any place that needs a little jellyfish.