This granny square has a very dense squishy texture. It definitely has a right and wrong side because of the front post stitches. It can be made using any yarn with the appropriate sized hook. In Stylecraft Batik dk yarn and with a 4mm hook my squares came out about 16cm x 16 cm / 6.5ins x 6.5 ins.I got 3 squares from each 50g ball of yarn.
The joining method will be on my blog in due course.