php - Unexpected Unicode Characters

one text

I'm trying to isolate where Unicode characters are coming from. I'm seeing the output of unexpected unicode character such as "x0030".

I'm reading a source Excel file in my PHP script and parsing the content.

Here is how I'm loading my Excel file:

//$file is of xlsx format
$spreadsheet = IOFactory::load($file);
$sheetData = $spreadsheet->getActiveSheet()->toArray(null, false, false, true);
$c = 1;
foreach($sheetData as $s)
{
    //first row are headers, thus skip
    if($c > 1)
    {
        debug($s);
        exit;
    }
    $c++;
}

Output of $s:

'A' => '_x0030_0013511',

The same file in Excel, looping each char of the string using a macro. The unicode is not visible looking at Excel:

Sub IterateCharactersObject()
    Dim ch As Characters, n As Long
    With Sheets("mysheet").Range("A2")
        For n = 1 To .Characters.Count
            Set ch = .Characters(n, 1)
            'print position#, character, font name & size to immediate window
            Debug.Print "#" & n & "=" & ch.Text, ch.Font.Name, ch.Font.Size
        Next n
    End With
End Sub

#1=0          Calibri        11 
#2=0          Calibri        11 
#3=0          Calibri        11 
#4=1          Calibri        11 
#5=3          Calibri        11 
#6=5          Calibri        11 
#7=1          Calibri        11 
#8=1          Calibri        11

Source