Antique 1600 -1868 Japanese Samurai Candle

Antique Edo Period 1600 - 1868 Japanese Samurai Candle ;
its fine quality ceramic type Clay thats fired & has the circular designs you can see, we are told its purpose was as a candle as oil was used ; exactly How I have never managed to determine?.
I have seen these sold at auction in Japan for upwards of Yen75,000 ; so they are very rare & I imagine collectable.
Width 60mm ;thickness 3.5mm.

Would love to know exactly How? these worked if anyone has knowledge ? please share and comment.

Thanks.