Contrary to what your title says, neither is the array blessed, nor does it contain arrays.

Actually it's a simple, unblessed array that contains blessed hash references. You can iterate over that array just like you'd do with any other array:

for my $item (@output) {
   print $item->{ID}, ' ', $item->{species}, "\n";
}
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But usually it's bad practice to access the hash items of an object - most of the time the object provides accessor methods that you should use instead.