Sprouts are hard/dead

Okay so I have 10 Durban poison and 10 indoor mix from nirvana. I germed em 20/20 germed all was good. I planted in rockwool PH coditioned to 6.0 in a tray with a lid, and the things started sprouting all is still good. Now here's the kicker some are great like 9 of em' but, 5 have cracked the shell, but instead of leaves they have a hard brown tip. Why? I have a lid on a tray and its humid also I have a new wave 2ftx4 T5's about 8 inches away. help I have more seeds to germ and plant. Is it just Nirvana's shitty seeds? Is that why I get 10 seeds for 24.00 bucks? I have much nicer more expensive seeds and want to fix this problem if its my fault. anyone else have this problem? Any tips?

I think that's the seed cover left on top of the seedlings, just wait another day or two and it should fall off. If it doesn't you can take it off yourself.

lol no the shells fell off it looks like a teeny tiny piece of amber at the top of the stalk the stalks ae turning brown also so I know they are dead or dying just not sure why? I tied to take a pick but all i have is a camera phone and you cant see it well at all. thanks tho.

they are 5 days old also

Only my seeds from Nirvana did this even the freebies were beter and all made it. WTF I have gone thru 40 seeds the last 2 years from Nirvana and each time I'm lucky if half make it 3 days past sprout. Got 4 jock horrors that made it out of 10. 2 of these were hard as sprouts, its like the two first leaves stay hard and only sprout an 1.5" stalk the shell falls off and there is this fossil looking thing that never turns green? White widow and 5 free skunks are nice and big and thick my 6/20 Nirvanas are small and wrinkly looking and all were germed within the same 3 days the Nirvanas being first and they are the smallest? anyone got any ideas? Please tell me it's not just me.