Kate, it does look like a button foot! But you're right -- it looks too old. Also, I just realized that it looks like the needle would hit somewhere in the solid part of the foot. I cut it out of the picture and placed it next to one of the other feet and the open part of the foot is quite a bit forward of the needle hole of the other foot. I've been looking around at various attachment sets and I can't find one with this type of "hardware" inside.