casting `Object` to `string` yields unexpected values?

[gewang]

"a".toString() => Object o; o $ string => string foo;
<<< foo >>>;
<<< o.toString() >>>;

"foo" => string x;
<<< x >>>;

prints somewhat unexpected values:

"string:6000024a5500 (refcount=1)" :(string)
"a" :(string)
"foo" :(string)