Does anyone know that it's actually asbestos ?

Don't be fooled by the color and consistency. Asbestos is a natural mineral that was used in many forms. One of the forms was thin white fibers, like nylon or cotton. They even used it as pillow filler at one time!!!
For the training I have had, one time exposure to it will not kill you or cause any health problems. It is only the prolonged exposure to it. Once it gets into your system, it never gets out, and on microscope it looks like jagged barbs cutting on your lungs.
So I would say, use a face mask, remove it, and dispose it properly.

 

some more advice if your going to remove it, whatever it is, use a face mask, put on a pair of disposable overalls and spray the material with some water to keep the dust down, maybe save a small bit and get it tested for peace of mind

 

I was told the stuff in my 308 was rock wool. Never heard of it but when I removed it I was crapping my pants thinking it was asbestos. Some else told me the stuff in the pic below from my boxer tail lamp is asbestos - looks identical to my 308 insulation. Needless to say I didnt violently rub it on my face while taking deep breaths.
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Even if it is rock wool, not asbestos, similar precautions should be taken. Here is a summary of safety considerations related to rock wool from Wikipedia:

Safety of material
Precautions need to be taken when handling a fibre product as it can be absorbed into the body by inhalation. It can also irritate the eyes, skin and respiratory tract. Prolonged exposure could lead to long term effects and it is considered a possible carcinogen to humans, similar to asbestos. This effect may depend upon the fibre diameter and length, chemical composition and persistence within the body.

 

Rock Wool contains asbestos. But don't panic. An isolated contact with asbestos is not going to give you cancer. It is way over cautioned. Sawing wood, installing fiberglass, breathing creosote, breathing any dust, without a face mask is just as equally dangerous. Just dont make a lot of dust and wear a particle mask.

I know people who worked in the Libby asbestos mine for years that never got sick. Others were dead and dieing. But that was a place with airborn asbestos fibers day in and day out and no breathing protection provided to workers.

 

Looks just like rock wool...often used for insultation but doesn't take the heat of asbestos, which incidently, is grey not yellow.

 

That definitely looks exactly like all that stuff I took out of mine, I was amazed how much of that stuff they managed to pack in there. I have kind of wondered if that should be a plus on resale value when that stuff has been removed, I am very certain that any modern type insulation you can buy nowadays is better than that stuff and definitely healthier.

Helmut