2002 S80 T6 Alternator Plastic Covered NUT

[django1]

I am trying to replace the voltage regulator on our 2002 S80 T6 and ran into problems taking this plastic/rubber covered NUT(attached similar pic found on internet). The plastic/rubber is almost totally torn up on mine, and it appears that the nut it covers is not HEX but round shaped. This is NOT the B+ terminal. The B+ terminal had a plastic/rubber boot that is removable and then a regular hex nut that holds the RED B+ heavy wire.

Does anybody know the function of this plastic covered nut? Why is it covered with plastic (or rubber), and why a round instead of HEX nut embedded in it? Is this some kind of anti-TAMPER device for warranty purposes?(i.e. warranty void if this plastic covered nut is removed).

Is it meant to be removed using a special tool (from Bosch maybe?)?
Thanks.

VolvoS80BoschAlternatorNUT.jpg (74.28 KiB) Viewed 420 times