class Foo
{
    public static $staticVariable = 'foo';

    public static function getVariableStatic() {
        return self::$staticVariable;
    }

    public function getVariableNONStatic() {
        return self::$staticVariable;
    }
}

We can not access

$staticVariable

using an object directly:

$foo = new Foo();
print $foo->staticVariable;

This will produce the following error message:

Notice:  Accessing static property Foo::$staticVariable as non static...

But there are several ways to access static variable using an object: 1. Using static getter method:

$foo = new Foo();
print $foo->getVariableStatic();

2. Using non-static getter method:

$foo = new Foo();
print $foo->getVariableNONStatic();

php.net:

A property declared as static cannot be accessed with an instantiated class object (though a static method can).