Thank you for the update!
If possible I would dig out the coriander that you planted in the same pot as the cannabis.
Coriander is a fast growing herb and could block light and steal nutrients and water from your girls.
Full spectrum lighting generally refers to light delivery across the entire visible spectrum of light. ... For the purposes of plant growth, the entire range of light provided by the sun is not utilized. Most plants absorb light across thefull visible spectrum.
If it's mold you're seeing soaking them probably won't help. I just meant for next time you decide to germinate. But give it a shot, it won't hurt anything.
The black you are seeing is probably mold.
You should never let the paper towel dry out, they should always be moist. Also try soaking them in a cup of distilled water for 12-18 hours before you use the paper towel method.
Your brother switch your cannabis seeds with something else and took yours!! Lol jk.
But they are cannabis seedlings, I have come across similar mutations in the past.
They will grow slowly but should yield at least an 1/8 - 1/4 :o