Ok I have found a skull how the hell do you pick them up?  I have tried
walking up to it but nothing shows to pick it up.  I just see the skull on
the ground and nothing else.  I am refering to the birthday skull on the
heretics station.

For those who don't know where this skull is it is on the level when you are
chasing the heretic and you are flying the banshee.  Fly right down to the
bottom of the station and find three rather large rocket looking structures
(quite large).  I think the middle one is where you find a bunch of grunts
dancing around in a circle (on top of the structure).  You need to look
carefully as they don't attack you when you approach.  I nearly flew right
past them the first time until I noticed something moving in the corner of
my eye.  The grunst are easy to knock off just blast em with the banshee
cannons.  Exit the banshee and walk up to where the grunts were dancing and
there is your skull.  Hmmm I think this one makes unsheilded enemies explode
when they die.  So if you shoot grunts they will explode.  This is handy if
you get one grunt in a tight group as when he pops the blast will damage and
possibly even severely injure the others nearby.