The purpose of these?

In my firewall there are these flat on the inside, and point in the engine bay, plugs kinda. I ripped out the old dampening and these were left in the car. I was wondering what is their purpose, they're black and made of metal. Can I rip em out? or cut em out? They're like nails, Flat and then skinny, I'm not sure how else to describe it.
 
They held in the old firewall insulation. I had removed my old insulation and cut my plugs out. They are kinda strong so you have to fight with them a bit. I filled the small holes with a dab or two of epoxy putty. There are holes in the front wheelwells (!) from these plugs so fill them too. I noticed some rust on the driver's floor that appeard to be partly from one of the holes in the wheelwell where the plug had been loose.
 
Thanks, yah, I removed one, and it was kinda tough and to use a mess of tools and a pvc pipe cutter to get it out. I'll get some epoxy, Really? above the wheel wells? For some reason my passenger's side has rust on the inside. I dunno why, The drivers side isn't too bad, I checked for a cowl leak, by pouring water into the cowl and it was fine, nothing came it, but when I put my head under i can see that there is some surface rust.
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thats a pain to clean up. I wire wheeled mine about 10 years ago and rustolemed it. It didn;t take long but was a friggen joke getting all the rust out of my hair. About a year ago I took out the heat and installer A/C and look just like yours. Go figure.
 
haha yah, i wear a turbine (im indian) so my head's usually covered, i have a work turbine cause it gets really dusty there, the worst is sometimes i forget to change my clothes, i usually go to check somethin out and refer to some diagrams on the comp but i end up moving things around and get grease on my nice white shorts :mad: .

I guess I'll get a wire wheel, clean the bottom, and rustolem it along with the firewall, and install the new sound dampening, and finally fill in holes that are no longer being used.

There are two screws that are using the firewall as a ground correct? cause one on the passenger's side is extremely frayed and by extreme, its freakn bad I think its from the starter motor cause its next to the transmission and behind the engine.