OK. Although I'm almost positive this pattern was not done by simple application of these two commercial (ie, $$$) plugins, if all you are looking for is the general look, these two will get you close:
#1 Alpha Plugin's "Engraver":
http://www.alphaplugins.com/products/products.php?menu=get_prod_id&p_menustate=&prod_id=2
http://www.alphaplugins.com/EngraverIIIManual/engraverIIImanual.php
#2 - Van der Lee's "Halftone":
http://www.vanderlee.com/plugins_halftone.html
http://www.vanderlee.com/plugins_halftone_screenshots.html
In both, note that many different spirals, circles, phase shifts, etc. are available as options
Obviously, one can enhance the results by using the output of one of these as input to the other, having different but related patterns in different areas using layer masks, etc.
That being said, there are fairly well known optical techniques used in microscopy, biomechanics, Ophthalmology, etc. to measure the shape of surfaces that produce patterns like these (see links below). Because the patterns seem to follow the three dimensional shape of the underlying material, I am suspicious that one of these physical techniques might have either been used as the starting point, or served as inspiration for this.
http://m.eet.com/media/1162619/137346-tmw05_06f2fig5_225px.jpg
http://link.springer.com/static-content/images/509/chp%3A10.1007%2F978-1-4614-5176-1_9/MediaObjects/106625_2_En_9_Fig31_HTML.gif
http://sstsg.org/uploads/3/1/0/5/3105842/1345730827.jpg
https://www.oapublishinglondon.com/images/html_figures/MusculoskeletalMedicine9-4.jpg
https://www.oapublishinglondon.com/article/606 (review paper covering various surface topographic methods in orthopedics)
HTH,
Tom M
