You can push down on the joystick-looking part to make the disk under it drop down a bit and spin quickly, flinging recently-deposited ashes into a container under it, if it's the kind I think it is.

Commenting to provide the info only because if my grandfather hadn't owned a similar one that I'd gotten to play with years and years ago, I'd have had no idea WTF they were.

[EDIT] "as" to "a".