I don't know what a "trans-borehole magnetic imaging rhubarb" is, but I want one. It's in the recipe, too, but for some reason the rhubarbs were not transcribed

I don't know what a "trans-borehole magnetic imaging rhubarb" is, but I want one. It's in the recipe, too, but for some reason the rhubarbs were not transcribed on that page.