wet cob I think, there’s actually lots of straw in parts of it around the house
it’s night so the color or yellow of straw isn’t really accurate here 
Discussion
Ah love it! Yes the straw provides tensile strength, super important part of the structure.
One of the coolest things I ever did was a workshop where we built a round cob hut with a reciprocal living roof, incredible experience I hope to repeat one day when we have land 😊