[RightWingAtheist]

A sundial is the first thing I thought of as well.

Regardless of what it is, it is definitely not an extraterrestial spacecraft.

[Political Junkie Too]

If it is a sundial, it must be very artistic since none of the markings indicate common time intervals.

-PJ

[Thinkin' Gal]

My first impression of the disk design (well, actually the 2nd, but that's been covered in the first posts) was that it was a chrysanthemum. The 16-petal chrysanthemum design is oriental.

Random link I pulled off of a Google search:

Sentiment & Symbolism The chrysanthemum has been the focus of Oriental adulation for centuries. In China, the chrysanthemum's association with autumn stems from its tendency to bloom in the fall. Consequently, the ancient Chinese chose the Chrysanthemum ("chu hua") as their Flower for October, a symbol of the rest and ease that followed the season's final harvest. Mums were considered one of the four Chinese "noble plants" (the others being bamboo, the plum, and the orchid), and were the official badge of the Old Chinese Army. Since chrysanthemums were considered the flower of the chinese noble class, they were prohibited in a lower-class person's garden. The Chinese believe that a chrysanthemum given to one's beloved, after its being used to wipe one's mouth after drinking wine, will ensure undying love and fidelity. Called "kikus" in Japanese, chrysanthemums were featured on the Imperial Crest of Japan, and were so beloved by Japanese emperors that they sat upon chrysanthemum thrones. The Japanese still hold the chrysanthemum as a symbol of the sun, and they consider the orderly unfolding of the mum's petals to be a symbol of perfection.They also presume that a single chrysanthemum petal placed in the bottom of a wine glass encourages a long and healthy life.

http://www.baacks.com/thelanguageofflowers/list.nhtml

The plant on the coin looks like an Easter Lily. So I Googled and got this:

Easter Lily

Lilium longiflorum, the Latin name for the Easter Lily, is native to the Ryukyu Islands of southern Japan.

The Easter Lily industry is an American success story. Prior to 1941, the majority of the Easter Lily bulbs were exported to the United States from Japan. World War II eliminated the dependence on Japanese-produced bulbs and commercial bulb production shifted to the U.S. The Japanese have never been able to regain any of their lost market share due to the superior quality of the U.S.-grown bulbs.

http://aggie-horticulture.tamu.edu/plantanswers/publications/lily/lily.html

Enough to say "Hmmm..." at least.