I replenished my wasabi today by purchasing another root / rhizome. With it this time came this oroshigane (おろし金 or 下ろし金 ), also known as oroshiki (下ろし器). It is a metal wasabi grater of the type which have widely replaced the traditional sharkskin variety - same no kawa orishikin (サメの皮おろし金) as shown above.
It is a fine grater but still rougher than the sharkskin type. No holes as found in western graters. I'll use both depending on application.