Blue Willow vintage Shenango restaurant china, Chinese style tea bowl cup & saucer

Heavy old ironstone restaurantware in the blue willow pattern, marked Shenango China. I think this is a tea cup (handleless cup) because of the saucer, but it might be an egg cup, or a small sauce dish?

The cup is 2 1/4" tall x 2 1/2" across the rim. Saucer measures 4 3/4" in diameter overall. Both pieces are in very nice condition, barely used.