Cactus pen from Mustard.

If you haven't developed a love of cactuses recently where have you been? The perfect plant, they require no watering and will survive more or less anywhere. If you're still not sure you can handle the commitment or the spines, why not get this pen instead? 

Green cactus pen comes in a plastic test tube, making it the perfect gift for your cactus lover friends and also helps to keep the pen upright to keep the ink flowing if you don't have a pen pot.

Novelty cactus pen features a black fine roller ball.

Test tube measures 39 mm wide x 160 mm high.

Cactus pen measures 30 mm wide at it's widest point x 150 mm high.