Knives are one of humankind’s most primitive tools. Made from bone, rock, or metal, their impossibly thin edges—sometimes just a few atoms wide—condense pressure into an extremely narrow space. That’s why a sharp knife can slice through a single line of tomato cells without squishing it. It’s also why about 500,000 Americans end up in the E.R. each year after cutting themselves.

However, a new letter opener by the Japanese design firm Nendo is designed so that it’s impossible to cut yourself on it.

[Photo: Akihiro Yoshida/courtesy Nendo]

Nendo has a particular knack for reimagining humble objects, ranging from rubber bands to sticky notes, into surprising forms that you’d never imagine. Its Nautilus Paper-Knife ($110) is no exception—even if letter openers are not the most popular object in a post-email world. Masahiro Ohgami led the design on this new letter opener, which features a 3D-printed shell inspired by mollusks (though I also see a spring washer in the form?). Grasping this curved shape should be more ergonomically comfortable than holding a straight handle. Then to actually slice open a letter, you slip the paper into a small slot in the shell. Inside, hidden far from your fingers, is a blade that slices the paper.It’s a clever design for a knife, with a shielded shell that literally makes it impossible to cut your fingers on the edge. Of course, the catch is that it can only cut paper-thin materials! So while your safely-cut raw chicken breast will have to wait, OXO does have another option for avocados, the single fruit which sent hundreds of people to the E.R. in 2019.