It's on one of the leaves on my seedling. I don't know what it is but it doesn't look right. Can someone tell me whats wrong?

I'll try to get a picture asap
TimidK Reviewed by TimidK on . Dark yellow bubble It's on one of the leaves on my seedling. I don't know what it is but it doesn't look right. Can someone tell me whats wrong? :( I'll try to get a picture asap Rating: 5