Those were floppies, too! The storage medium was a flexible magnetic film, same as floppies and unlike the rigid platters found in hard disk drives.

SyQuest competed with the ZIP drive with its EZ Drive, which used a lone hard-disk platter in a removable plastic cartridge as its storage medium.

Both drives suffered from various mechanical problems, high cost of storage media, and low storage capacity, and were ultimately outcompeted by optical discs, which have in turn been replaced by USB flash memory cards (although optical discs are still useful when you need to receive some bytes from someone you don't trust not to destroy your computer).