Sentinel Conversions for the Genestealer Cult

While I work on the bulk of the infantry, which are getting close to done now, I thought I'd show the Sentinels.

All of the vehicles will have 'tyranid infestation' but for the sentinels I had an idea for something a bit different.
Most builds for the sentinel are open-topped, where you can see the driver. Rather than put one of the mildly mutating infantry in there, or closing it up and treating it like the other vehicles, I thought of this fellow:

Not that I'd put an actual hermit crab in the sentinel, but not all tyranid creatures are tough as nails.  

I imagined a smart but soft species that would use shells, perhaps from dead carnifeges for protection.  

But in the case of overwriting human dna in the manifestation of a Genestealer Cult, this breed of tyranid has a lot more options.. and some of those options have guns!

So here's my brain & tentacle creatures piloting their fancy new shells...

(Click for larger)

This one (stompy) is in the act of walking forward.  I usually see sentinels with both feet firmly planted to the base but I don't know why.  The legs can be posed, the head-hull can be rotated a bit... can get some feeling of movement from the model. It is supposed to be a scout after all. 

This one (runny) is in more of a full-tilt headlong run, but turning his head a bit to the right to take a shot. 

One of my favorite machines from Star Wars is the AT-ST, and how menacing they looked stalking the forest of Endor, so I've tried to bring some of that to these.  

The bases are painted already, they'll be combined after the vehicles are painted too.