A very small avalanche on Mars...
May be old news, but "Microkid", one of the posters on Doug Ellison's Mars site has found an interesting "before-and-after" pair of images showing that Oppy is dislodging spheroids which are rolling downslope and leaving tracks - including curveballs and skipping tracks.
Before:
After:
There are also some other filters in the same series as the second shot, which show the tracks in a different light, as it were.