Caterpillar nest with webbing and frass

Here is the nest of a caterpillar under an oak leaf with webbing. I suspect that it's the work of a caterpillar because of the abundant frass (or poop) off to one side, but I can't see the critter in its nest. We seem to have a number of different caterpillars that spin webs in the oak leaves, compare this photo and this photo and this photo. I already have my two photos for the Web Wednesday group, but HWW anyway! (San Marcos Pass, 23 March 2020)

Done