Pebble Characteristics - Shape Irregularity

The irregular shapes of pebbles are a topic of great debate among geologists.

Some pebbles are smooth and spherical, like the perfectly round pebble:

But others are more, well, irregular:

Pebbles with Bumps Pebbles with Cuts Pebbles with Holes Pebbles with Tangles

And then there's the Pebble Unicorns, because, why not?

Pebble Unicorns