Strange head jewellery

Some pictures are not very interesting from an aesthetic or art historial point of view, but have other interest nevertheless. This family portrait, for sale at Bukowski's with an estimate of 1,200 Euro and a current highest bid of 500 Euro, described as Baroque (style), 18th or 19th century, is fairly mediocre. UPDATE: it was not sold and has been relisted.

But what is the strange thing on or around the head of the woman? Some Star Trek inspired communication device? A medical thing? Jewellery, some strange parure? Her necklace is rather peculiar as well, with some collar on top of it apparently, but the head decoration is the most curious thing I have seen in a portrait in a while. I presume it is something they considered to be decoration, why else would you show it in your portrait (in those ages, nowadays you can find anything in portraits)?

The most likely explanation seems to be that it is some kind of "oorijzer" (ear iron), an element of Dutch traditional dress, normally meant to keep the headdress on the head and in shape (example of an oorijzer covering the ears in a 1636 portrait by Jacob Cuyp). On this portrait, the couple is shown in prayer, and this means that the headdress needs to be removed. Possibly the oorijzer was exempt from this, and only the actual headdress was removed, resulting in this unusual picture. I certainly can't find any other example of this anywhere, making this painting probably fairly interesting for institutions or people specializing in costume history and the like.

A somewhat similar element on the forehead can be seen in Rembrandt's portrait of Margaretha de Geer, in the National Gallery in London (detail pictured). But none of these portraits looks so strange as the one for sale here.