Q:

What does The Butlerian Jihad's coverart depict?

The first book of Dune's prequel series depicts a sand worm, a classic motif of the Dune books. After reading the book, one thing kept bothering me. 
What is the object in the mouth of the sand worm?
Here is a close up of it: 
It seems as though it may be the probe that Omnius dispatched to Arrakis, but the book mentioned nothing about the probe retaliating to the worm with its defenses.

A:

It certainly appears to be Omnius' probe. Note that it did get off a few shots and although there's no indication in the book that they hit, book covers are notorious for not being wholly accurate...

The crashed probe continued its pounding, rhythmic motion with a clattering of components, oblivious to its surroundings. The assembled mechanism raised itself, a monstrous composite of crystalline materials and silica struts reinforced by carbon-fiber beams converted from its own hull and support girders.
The sandworm came in fast, tunneling just beneath the surface until its head rose up. The mouth was a huge shovel larger than the impact crater.
The robotic probe waved its sensor arms and weapons lenses, sensing it was being attacked, but not understanding how. Several white-hot blasts of fire penetrated the loose ground.
The worm swallowed the mechanical demon whole. Then the sinuous desert creature burrowed beneath the dust again like a sea serpent seeking deeper waters…

