Todd Spangler NY Digital Editor The battle between Elon Musk’s Twitter and Mark Zuckerberg’s Meta over the launch of Instagram’s Twitter rival Threads has taken a legal turn. On Wednesday, Meta’s Instagram debuted Threads, a text-focused social app designed to piggyback off Instagram’s infrastructure and user base. The app had more than 30 million sign-ups as of Thursday morning, according to Zuckerberg. In a July 5 cease-and-desist letter addressed to Meta CEO Zuckerberg, a lawyer representing Twitter said that Musk’s company had “serious concerns” that Meta “has engaged in systematic, willful and unlawful misappropriation of Twitter’s trade secrets and other intellectual property.” The letter said that “Twitter intends to strictly enforce its intellectual property rights, and demands that Meta take immediate steps to stop using any Twitter trade secrets or other highly confidential information.”