Turns out that a new resident has moved into the garden. A frog has made himself at home in the Mioshi Post lantern.
I'm not sure what type of frog he is, but I have seen hime crawl out at night and walk along the edge with his suction-cup like feet. Interestingly, he is able to change his colors to match that of the granite of the post.
I like him, so I won't be lighting any candles on the lantern anytime soon. With luck, maybe he will come out at night and hunt down slugs.