The pins, neatly spaced in a vertical line down the star's auricle, may look like trendy new jewellery, but they are in fact acupuncture pins that are attributed with myriad health-giving properties.
The needles are used for auriculotherapy - a form of acupuncture that stimulates points in the auricle (the external ear) in order to alleviate health conditions elsewhere in the body.
Alternative: Penelope Cruz was last night spotted with acupuncture needles in her ear - a sign that she is undergoing auriculotherapy. It remains a mystery what she is having treated, but the method is commonly used for smoking addiction, pain or to help with fertility
Treatment: The needles are placed in a vertical line on the star's auricle, and seem, according to a map devised with points corresponding to different parts of the body, to be the treating knee and back area and assistnig muscle relaxation
Increasingly, the therapy is being used by fertility experts to assist women who might be struggling to conceive.
One of the most obvious - and simple to explain - uses for auriculotherapy is to help quit smoking.
The user wears the needles in the ear and, if they feel the urge to smoke, they simply press or twist the needles.
Practitioners also report excellent results with weight loss and weight management, where the needles are used to help dieters curb cravings and halt binge cycles.
Pinpoint accuracy: The map, devised by Dr Nogier 50 years ago, combines Eastern and Western medicine to devise a treatment using needles to stimulate reflexology points
When Dr Nogier was presented with a patient with strange cauterisations in his ears, he questioned the man who told him he had self-treated his sciatica using an adapted version of Egyptian learnings.
Dr Nogier developed the treatment further, devising a map of the ear - which he found resembled the shape of an upside-down foetus - that featured points, each of which corresponded to a different part of the body.
Happy couple: Penelope married actor Javier Bardem in 2010 and the two have one son, Leo Encina
She married Javier Bardem in 2010 after dating for three years, and the pair, who are notoriously private, had their first child, Leo Encinas Cruz, in 2011.
Using Dr Nogier's map, it appears as though Penelope's needles could be placed in the zones which would correspond to muscle relaxation, the lumbar and thoracic spine, the knee and the occiput, which is the back region of the head - pointing at potential treatment for back pain.
The needles, which are very fine and can not be felt day-to-day while they are being worn, do not hurt once they are in the ear.
The patient may feel a very slight pricking sensation when the practitioner inserts the needle, and some report a certain level of discomfort when manipulating the needles. Otherwise, it is entirely pain-free.
The treatment was officially recognised by the World Health Organisation (WHO) in 1987.