Canal Worms

It seemed that canal worms had died out on the Mars of the late 19th century. However, once filling the canals with fresh water, the adventurer will get an ugly surprise. These worms have survived in hibernation and are now back!

Description
These huge worm-monsters surely are fear-inspiring. At least ten meters tall and as thick as a big tree trank, their teeth can cause high damage and it can swallow a person in one move. Thankfully their worm body is also their bigest weakness, as far range attacks will kill it quickly, barge cannons being the most effective way to do so.

Found in the canals once they're re-flooded.