Just a concept I was throwing around in my head, trying to exercise my ability to design vehicles and creatures at the same time.
A bit stuck for time so no long descriptions about this one at the moment, but essentially its a pirate cult's means of finally being able to break through the more protected (and therefore, higher loot quantity) towns that had previously been able to deter these scrappy invaders with little concern or effort. Until now...

Drawing inspiration from the Tide Eater's symbiotic relationship with a local crab species, where the crabs would burrow into the shells to find greater protection, safe haven to spawn, whilst in turn aiding the Tide Eater by feeding on the parasitic organisms that reside within the shell. Over time, the Tide Eater's shells began to enlarge and accomodate these crabs, who would seem to create caverns whilst at the same time, curiously causing no pain to the tortoise.
The cult, who had previously used the Tide Eaters as simple hauling power, began to experiment by cutting away fragments of the shell and carving through the areas which were once inhabited by the crabs, in order to accomodate a human shape. The tests proved fruitful and very soon afterwards, the brute force stopping power and easily disciplined turtles had the potential to become armoured land transport vessels - and double as a determined battering ram against the wealthy merchant towns walls. Once cracking open the defensive barriers, the soldiers paled in comparison to the eager and experienced pirates who would emerge, grinning, from the tortoise's shell.

Apart from evident amounts of armour plating reinforcement and some bulldozing headgear, I equipped the Tide Eater APC with two gun posts for self defence, as well as multiple peek holes for observation and/or firing from. I threw in a rudimentary smoke dispenser, which is operated with the burning with herbs that create a thick white plume of smoke, but also acts as an irritant - and if anything, looks more intimidating to rich people who are about to get pillaged.

Ugh, so much for me not talking so much! Enjoy!