Nothing is known about the Rigelian sandworm other than that it's presumably a worm, presumably lives in sand, and that it is helpless in water when it has no bicycle. The creature is known to the Romuclans, who compare the helpless combined Moldhammer/ Kickstart to it.
Behind the scenes Edit
The nature of the creature is unclear, on the one hand, it is called a (sand)worm, and as any worm, it should not have limbs, but on the other hand, it's implied to be able to use a bicycle, which actually requires limbs to operate. Obviously the creature was created to be bizarre for comic and possibly other-worldly effect.