Seed caps, seed caps.....
Depending upon the size of the plant and how the seed cap is stuck on, the plant could end up dying. Since you said you started more than you have capacity for, first choice would be to toss the ones that still have seed caps. But if there are some that you particularly want to save, you can try to CAREFULLY remove the seed caps yourself. First spray them with plenty of water to soften the cap, then pinch the seam with a pair of tweezers to widen the opening, and GENTLY pull. If it won't come off easily, stop, as pulling the cotyledons off most likely will kill the plant. Try again in a day or two, or at least soak with more water first.
If the seed cap is simply stuck to one of the two cotyledons and true leaves have started, though, it shouldn't be a problem.