"I noticed several thumbnails where the poser girls
had these knobs sticking out of their heads. I don't know if this
was an hairstyle, an helmet or maybe head morphs."

I'm not sure what you're referring to, but could it be the weird thingies sticking out of Victoria's head in this render? If so, that's part of a cute sci-fi costume that IIRC is no longer available. I'm pretty sure it was ISOP's, but if anyone rembers with certainty, perhaps you can remind me of where I found these.   :-)