A compact audio cassette next to a microcassette. (Image: Malcolm Tyrrell/Wikimedia Commons/CC BY-SA 3.0)

Chicago composer Olivia Block has a thing for micro cassettes, those tiny tapes that used to go into answering machines.

As NPR reports, her fondness for the outdated technology began when she purchased an old tape recorder on eBay that contained an unlabeled micro cassette with a man’s voice on it. She still buys micro cassettes from eBay with the hope that, though they’re supposed to be blank, they’ll still have recordings on them. 

“There’s something about these little tapes…people really used them for personal uses,” Block told NPR producer David Schulman. And even without the voices, she really likes “the noise of the machine itself”—the whirring, shuffling and clicks that make the technology “reveal itself in that awkward way,” Block said.

Many of the recorded sounds are the sort you’d expect on answering machine tapes: practical nuggets telling callers to leave a message. But sometimes they’re a little weirder: the NPR segment, embedded below, features an eerie recording of someone whispering into the answering machine.

Bonus finds: Space fungus, bacteria in the stomach of Otzi the Iceman, mountain lion with teeth sticking out of its head

Update, 1/8: An earlier version of this story incorrectly identified a TDK MA-R90 cassette tape as a micro cassette. We regret the error. 

Every day, we highlight one newly lost or found object, curiosity or wonder. Discover something unusual or amazing? Tell us about it! Send your finds to sarah.laskow@atlasobscura.com.