In WH40k, a stratagem is a token that represents some sort of objective in the game. In the venerable Space Hulk, there is the corpse of a space marine sitting on some sort of throne...very cool. Other stratagem are a bit more mundane: a pile of ammo, a drainage pipe, a small artifact, wreckage, etc.
So I was looking around my office last night, just cleaning up and watching Adult Swim, when I came upon a box full of shells that the kids collected when we went to Naples, Florida last year. They gathered a TON of shells, many of which were damaged, ugly, or both. Inspiration struck, and my plan is to use a large base and create a Carnifex fossil utilizing an extra head from the Carnifex I just completed (there were 6) and some of the shells that looked alien. There was even a little mutant crab claw in the box! The genetic material in this fossil would be incredibly valuable to interested factions - Eldar and the Xeno-haters, most likely - so this fossil as a stratagem makes a bit of sense, at least.
More this evening as I get cranked up on this.