What is the line of foam under the vents and thunderbolt 2 port for?

I opened my Late 2013 MacBook Pro yesterday for the first time and brushed the internals with a toothbrush. I noticed some build up on the thunderbolt 2 ports and scrubbed it, only to realize they’re actually some kind of lining similar to that spongy foam under the vents.

So I accidentally destroyed that lining, and to be fair it was already dry and brittle probably due to heat and age, and I know it probably isn’t crucial to the device’s operation, but does anyone know what is it for? Is there anyway I could get a replacement?