The Recording Industry Association of America passed a new milestone this week, sending Google its 50 millionth request to remove what appeared to illegally uploaded material from its search results. The chief target, not surprisingly, were popular file-sharing pages and sketchy ringtone sites that have been in trouble in the past.

The RIAA and other copyright protection groups send Google monthly requests to strike search results that facilitate piracy or otherwise illegal activity. Past targets have included the Pirate Bay, KickAssTor, and other potentially shady regions of the web. The most recent requests centered on similar, albeit less frequented webpages.

Filestube.com, which bills itself as a storage locker on par with MegaUpload, was the most targeted page, with 1,914,332 pages that the RIAA hoped would be blocked. The popular MP3 download site MP3 Skull was targeted 1,314,953 times, and BeeMP3 (where an estimated 10,000 files are added every day) was the subject of another 1,266,121 requests. Pisamba.com (1,562,263) and Downlaods.nl (1,535,067) rounded out the top five most specific domains, according to Google’s transparency report.

Google generally wastes little time in complying with such requests, though the removed searched results can sometimes be found at the bottom of the results page when Internet browsers are told that certain sites had been taken out of the selection.

“Google regularly receives requests from copyright owners and reporting organizations that represent them to remove search results that link to material that allegedly infringes copyrights,” the company said. “Each request names specific URLs to be removed, and we list the domain portions of URLs requested to be removed under specified domains.”

In marking the 50 millionth takedown request, it’s clear that the RIAA and Google are familiar with how the other operates. Yet the copyright organization’s CEO Cary Sherman has complained that, even with thriving streaming services like Netflix and Pandora, the number of necessary takedown requests is sometimes insurmountable – especially when it comes to sites like MP3 Skull and Filestube.

“All those links to infringing music files that were automatically repopulated by each pirate site after today’s takedown will be re-indexed and appear in search results tomorrow,” Sherman said before, as quoted by TorrentFreak. “Every day we have to send new notices to take down the very same links to illegal content we took down the day before. It’s like ‘Groundhog Day’ for takedowns.”