Little plants

Sometimes ago, I used my old pot to plant some chili seeds but they didn't grow up for a while. Meanwhile, my labmate needed a bigger pot for his plant. So, I had just gave the pot to him. After a few months, he told me that were some little grass growing up inside the pot. Therefore, I decided to take them back last weekend and try to see what they really are. I took 12 back and at the first day, 4 little guys were down. At second day, three more were down. It seems like I have either overwatered them or chilled them by putting them too close to the window. Well, I am just not very good at gardening.