Just adorable! A complete set of six Walter Bosse style vintage stacking metal hedgehogs.
Designed by Walter Bosse in the 1950s these are the Russian copies/interpretations, probably 1960s to 1970s vintage. (The design was not copyrighted). Looking on the Modern Vienna Bronze website, these look to be the Russian ones made for Aeroflot airlines which were given away or sold as 'souvenir ashtray hedgehogs'.
Likely zinc metal, the raw silver coloured metal had the addition of darker applied black colour and polishing. There are details in the casting on the spines, eyes, ears etc, see photos. This cast metal set intended as a set of six ashtrays, but more ornamental and for display. Stacked - 11 x 7 x 7cm. 
They're in very good vintage condition with not too many signs of age or use. No maker's marks to the base. Black and grey colourings with silvery trim.
Price includes P&P to the UK.