Sons of R'lyeh - CSM Concept

So this is an idea for a CSM Chapter that I have been toying with for awhile. I love the H.P Lovecraft Cthulhu Mythos, and have read just about everything Lovecraft has written. I wanted to do something a little different than the normal tyranid cthulhu guys.

The Sons of R'lyeh

Background: It is believed by Imperial Inquisitors that the Sons of R'lyeh Chapter are an off shoot of the Notorious Alpha Legion. Shortly after the heresy three companies of Alpha Legion were attacking an unknown Oceanic world. Shortly afterword one of the Marine Strike Cruisers was mysteriously destroyed, the other two left the planet shortly thereafter, leaving the indigenous population intact.

Since that time the Sons of R'leyh have been sighted numerous times, mostly near large world mostly covered in deep oceans. They almost never engage in direct conflict, usually leaving the planets population alone. The only lasting sign of the marines are the small cults that are left behind, remaining mostly hidden from the general populace.

Modes of operation: The Sons of R'lyeh rely heavily on the use of cultists and mutants in the few battles that they do fight. It is believed the Chapter numbers under 100 marines. The chapter also seems to conflict more with the other followers of Chaos than Imperials, the cults usually stamping out any other chaos cults on the planets.

Without further ado, a Son of R'lyeh:

What do you guys think? Should I continue with the project? I do want to add some barnacles and stuff on the armor of the marine...

EDIT: The painted marine can be found Here