merry X-mas, and unidentified gasket in head set

[Konstantine Bogach]

Merry Christmass to all and thanks to all for continuous help!

I need one again.  I can not recognize one gasket from head gasket set:
it is made of black rubber, has round profile like O-ring but has
trapezoidal shape (distorted rectangle). I don't remember seeing it when
I took head apart.  Anyone know what I am talking about?

Thanks.

Konstantin Bogach.