Doctor Who s9 prop - zygon grenade

This is a concept for a prop I designed for Doctor Who series 9 in 2015. This was a living smoke grenade thrown by a Zygon. Sketch & Painting; I imagined it as a creature that lived in the Zygon ecology.
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I concepted a load of props on Doctor Who series 7 - 9 (2012 - 2015), will upload and attach more here.