It's the Isokon Flight Stool!

An Isokon Flight Stool spotted in a Design Museum post celebrating Halloween.  The Barber Osgerby designed stool was used in a campaign by Pantone featuring the stool screen printed in different Pantone colours.  The Stool is in the Design Museum permanent collection and this one was created in 2005 in pumpkin coloured Pantone 16 - 1364 TPX.