Just an observation to share...
I manage the communal gardens in a development in Prodromi, on the western edge of Cyprus. This time of year, I spend a lot of time picking up the fallen fruit from the citrus trees. One of the sour orange trees, which had a crop of several hundred unremarkable fruit, had one exceptional one. It was about twice the diameter and very lumpy.
I guess fruit, like shoots, are subject to one-off abnormalities/sports. My photos show another such abnormality (a straight recessed greenish line). I would be intrigued to know where on the tree the lumpy monster came from, to see if more such fruit arise from it next year. But being a windfall, I'm out of luck on that score.
BTW, I there is a mandarin called 'Golden Nugget', which looks quite similar
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http://farm6.static.flickr.com/5093/5587988886_1a3c95794a_z.jpg[from
http://www.foodlibrarian.com/2011/04/golden-nugget-mandarins.html]
Unlike that, however, my fruit has a very thick rind (last photo).
Mike