What kind of insulation is this???

This insulation was in a 1955 home in Utah. It was covered by fiberglass batt and I’m not sure what it is. It looks like it is fiberglass based but it looks like it has grass/bark in it?? I took home a sample because I wanted to test it if it was flammable or not. It turned out to be very flammable.

Any advice of what type this is or if it is even insulation would be much appreciated!:smiley:

Kerri Tennant 017-400.jpg


Thanks Dale, I appreciate it!