The Marathon Bar was a full eight inches of braided caramel covered in milk chocolate. Mars introduced it in 1973 and thanks to its bright-red package and extra long size, it stood out among the competition. Inch markings printed on the wrapper showed just how long it actually was.
The length was the result of its braided shape but it didn't actually weigh more than standard candy bars of the time. When sales didn't meet expectations in 1981, Mars discontinued it.
http://www.oldtimecandy.com/curly-wurly.htm