>>296187Keep a desklamp and a low/medium watt lightbulb maybe a foot or so away (I don't want to take risks and I've seen sites that say 6-8 inches away but I think its too close so I go a foot or more away) to ensure your plants get necessary light. I did this and my corn seedlings turned from yellow to green in a day and I can see the outlines of the true leaves now.
See if the watermelon seedling will still grow... don't give up hope on it just yet. I see about 5 watermelons in 2 holes, those are them, right? They are definitely outgrowing their container its too bad you put so many in a small space but don't give up! The first two leaves (seed leaves) show up first and you want the true leaves (they come next after the seed leaves) to grow and I see one of two on some plants. At that point, The root system should be established and its safe for em to be removed (if you're careful) from the container. I'd put them in a jiffy pot right away and as soon as you get 3-4 seed leaves, its time to put it into the soil so the main root grows deepest and stabilizes the plant. I had to do this for my corn and sunflower as they outgrew their peat pellets 2 days after they sprouted.
Those tomatoes on the right look like you can try. Get a pencil with the eraser end and push the bottom part of the soil and lightly squish it until the soil cell pops out with ease then you need to use the soft brush bristles and CAREFULLY expose the roots without breaking or cutting them then transplant.
For the plant with the seed still stuck, lightly mist the leaves & seed coat and it helps the plant push it off on its own. Also, with light, as the leaves respond to the lamp, it will help them 'push' off the seed coat on their own. You don't want to accidentally decapitate it by trying to help! My sunflower had trouble but its doing work on its own thanks to light and moisture to help push the seed coat off! They're in Jiffy pots and will go outside a few days after true leaves form
