Poond

Hi, a year ago I had a harmonic balancer fail and I replaced it myself and car is running fine. However now that I have seen a few more YT videos I realise that the big bolt through the middle, crankshaft bolt?, is missing. I am guessing that isn't good...i attach a picture of the crud that was on front of the pulley. So is there supposed to be a big bolt in there too can? can someone advise please?