I think what the artist did was use a circle mold and carved out the spaces when the clay was leather hard. It's an interesting technique because they look hard to do, but once you begin you get the hand of it, and they make cute candles.
Easy tutorial to use make a drift wood orb. Use a hot glue gun and glue them around a beach ball. When your almost done, deflate ball, remove and close the hole with more drift wood. What a unique way to decorate a room!