Urturn, the social expressions platform that soft-launched as stealthily as possible last year by intentionally hiding under a really boring name, is getting ready to turn the volume up to 11 to start seriously recruiting teens and trend-setters to its meme-stuffed, fashion-friendly, music-loving platform. Today it has announced a $13.4 million Series A funding round, led by Balderton Capital with a $10.7 million investment. The private equity arm of Debiopharm Group invested the remaining $2.7 million. As part of the investment, Balderton founding partner Barry Maloney will join the Urturn board. The London-based startup, which also has an office in the Valley, is also launching an iOS app today, funded by its Series A, to extend its web-based platform to mobile. An Android app is also in the works, due later this year. Prior to the Series A, Urturn had raised around $500,000 in friends/family funding. So what exactly is a social expression platform? Urturn — pronounced ‘your turn’ — is best described as a viral meme-generator. It offers both a social toolbox for creating and sharing ‘expressions’ with other users, with support for sharing these out to other social networks such as Facebook, Twitter and Pinterest, and also a space to hang your creations and browse others (and/or follow celebrity users or your friends). It also has its own bookmarklet browser button to make grabbing source material for meme-making purposes even easier, as Pinterest does. Expressions is Urturn’s term for the visual composites that are its social currency. These often start with a photo but can also include multimedia elements like video and audio, which are then augmented with text or doodles or other graphical elements, by a user selecting the relevant template. So, instead of having to go to Google to copy and paste the meme du jour to post to Facebook or Twitter, Urturn gives its users the tools to make their own version of that meme. Or something else entirely. The image at the top of this post is a basic example of an expression created with Urturn — by first uploading a photo and then adding a series of pointers to the image. Other templates currently available on the site include doodles, collages, quotes, speech bubbles, hashtag tags, cartoon elements (such as the Bunnify expression, below right) and more.  There are also templates that support interactions, such as love it/leave or this/that which ask other users to vote on whether they like