odd form splintered at one end

[Marsrocks]

I have no idea what category I should put this odd shape in, but it appears to have an interesting form, and it looks splintered and hollow on the left end of it.

Curiosity sol 528:

mars.jpl.nasa.gov/msl-raw-images/msss/00528/mcam/0528ML2087014000E1_DXXX.jpg