Thanks so much for your advice. We removed it, and it came off very easily. It was hanging by a thread (or feather... so to speak). We cleaned it all up and she seems much perkier and back to her usual self now.
My husband and I noticed that one of our chickens was acting lethargic so we gave her a mini examination only to find the above growth by her vent. She seems to be able to still poop, and walk around normally, but we are not sure what to do now. We gave her a warm water bath and let her butt...