A closure assembly for closing an opening in a container includes a closure member including an engagement structure configured to engage the opening. A tether includes a connector portion, a first end, and a second end. The first end is coupled to the closure member and the second end is opposite the first end. A plurality of barbs are positioned at the second end of the tether, each of the plurality of barbs has a rigid construction. The plurality of barbs define a maximum splayed dimension to retain the closure member with respect to the opening. A movable joint couples each of the plurality of barbs to the second end. Each of the plurality of barbs is foldable about the respective movable joint so that the plurality of barbs define a dimension substantially smaller than the maximum splayed dimension to allow insertion through the opening.