Insect and Spider Identification: Termites? Oh no..........., 2 by jeffpas

jeffpas wrote:
Okay I was adding a small entry door to my garage (have lived at the place over 15 years) and had just cut a section of the wall out which used to be a window.
When I tipped the wall section out, it ripped off the concrete foundation and guess what was underneath- this very curious thing. Though nothing was visible inside the garage, a section under the foundation board was hollowed out and all this was there.

I didn't see anything moving, and the only insects I could see were a few large red things which appeared dead.... though it was awhile before I had had a good look.
Carpenter ants? Termites? Water rot.... Trying to figure out what is going on and how much of a danger this is......and then what should be done. Anyone recognize what this is?