It looks like an embryo.
Drain the liquid and the embryo. Hopefully the yeast is okay. If that is all I had, I would use it and hope for the best. Good luck.
Every bottle will have a yeast cake. That is bottle conditioning. Now, how big is your bottle and how thick is the cake?
Also, pour your beer gently from the bottle into a glass. Leave the last 1/2" of beer and yeast in the bottle.
I use a refractometer to make sure I get the beer where I want in the beginning. I don't check final. After 3 weeks it better be ready to bottle. Terrible practice? Probably, but I haven't had any problems in two years.