First Test Design
At the very beginning it was planned to make the Grievers as big transformer-like robots. However I had already created this test design in my free time, before I got the job, which showed the hybrid creature idea from the novel. I presented the design to Wes and he loved it. I pretty much completed the design in this first concept, we only added a mechanical scorpion tail afterwards in order to make them more threatening. Slugs and coconut crabs were a big influence for me in finding the overall body shape. The head is a mixture of caterpillars, bulldogs and piranhas. Later Method Studios came on board and used my designs for the VFX.
I did plenty of these different pose sketches, which illustrated how the creature could move. The wizards from Method Studios enhanced the movements to perfection.
Since we see the Grievers mostly in the dark, Wes wanted to find a way to illuminate them with some kind of 'light dots' and sensors. This is one of a few options that I had sent to him. One idea was to put these lights underneath the slightly translucent skin which would constantly move in one direction.