Additional to hippo's answer:

Most languages implement objects as "blessed" hashes, and that's also the overwhelming case in Perl.

But in Perl you are free to use any reference as a container for the state of the instance.

And that's what is happening here, you have a blessed scalar (ref)

See bless ...

update

... and perlobj#An-Object-is-Simply-a-Data-Structure

> Objects are merely Perl data structures (hashes, arrays, scalars, filehandles, etc.) that have been explicitly associated with a particular class.

> That explicit association is created by the built-in bless function, which is typically used within the constructor subroutine of the class.