uhm, i pulled these out of my heads...

ok, so im replacing the valve cover gaskets on my ride, right, i pulled the covers off and i figure i should look it over while im here. i find these little bits... im like "wtf?" so i get a flash light and find all of them i can.
http://bellsouthpwp.net/r/a/rabius/****.jpg
and...

i found some on top of both heads, but i cant find the bits i pulled out of the passenger side, lost them while painting my valve covers.
they feel like really hard rubber, and if i put them down and push on them, they give a little bit and return to their original shape. this is kind of worrying. i plan on getting some magnum heads in the next month, but this worries me...

any idea what they are? is it a valve seal or something.... what?