What kind of matrix barcode is this?

I first assumed the image below was a QR code, but upon closer inspection, it seems to be something else (note, for example, the calibration square in the middle of the matrix).

Does anybody know what such a dot matrix is called? Are there any tools available to decode it (Python would be ideal...)?

Many thanks!

This barcode symbology is Aztec, as @Hacketo pointed out. Characterized by the finder pattern made of concentric square rings. Specifications for this symbology can be found here: http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=41548

ZXing is a very popular open source option for barcode recognition. They have beta support for the Aztec symbology. You can access the github project here: github.com/zxing/zxing

I've seen some Python ports of this library however they seem to only support QR. github.com/holizz/pyxing granted no commits have been made in a while.