It is day 24 and my last chick just hatched. It appears to have an opening above his vent. At first I thought it was something like a short stubby tail like thing b/c it was moving up and down. As I'm writing this I'm realizing that this may be the exact location where the oil gland is on chickens that people make sure they cut out before cooking. Also it does look like an oil substance is slowly dripping from that area. I haven't taken him out yet to inspect closer. I'm hoping that it might work itself out in the incubator. Not sure what to make of this just yet. What do you guys think?