If those are cephalopod eggs then they are certainly nautiloid. None of the other cephalopod groups had evolved at that early date, not even the most primitive ammonoids. However, precisely what form of nautiloid is impossible to say as they were quite a diverse bunch of animals back in the Ordovician. Mastigograptus appears to date from the Middle-Upper Ordovician, something like 470-443m.
I found the original reference to these if anyone fancies tracking it down (one might have to travel to Poland though!):
Kozlowski, R (1965) Oeufs fossiles des cephalopodes? Acta Palaeontologica Polonica 10: 3-9.
I'd be surprised if they were cephalopod eggs as according to Regis Chirat in his 2001 paper Anomalies of embryonic shell growth in post-Triassic Nautilida no fossilised nautiloid eggs have ever been discovered. Unless Chirat missed these in his paper which looks extremely comprehensive, one can only assume they have been reinterpreted.
In the above reference, a recent very detailed revision of Mastigograptus (and far, far too complicated for me) there is a brief mention of the eggs but it does not add much about the eggs themselves. Graptolites, long extinct, were bizarre colonial invertebrates that consisted of branches and tubes containing individual animals linked to a single invidual which was often anchored via a disc to the sea bed or rocks, though other forms were probably planktonic floaters. Some looked like leaves, others disks, and still others like sticks or miniature fan corals (though they were probably Hemichordates and very distantly related to the vertebrates).
As for Mastiogograptus, that appears to be a peculiar form of early sessile graptolite attached to the sea floor and appears to be somewhat problematic amongst those who study these things.
Just so happens that a certain Polish friend of mine is checking out the Polish fossil scene over the Xmas holiday, if he gets time (at -25 deg.C it may not be a priority). As Tonmo's unofficial eyes & ears on the continent I will endeavour to bring home the bacon ! :D
That'd be fantastic, wouldn't it. You know, it really seems very strange that we haven't found ammonite soft-body parts before. Even in sites of exceptional preservation such as Solnhofen in Germany, we have soft-body fossils of belemnites and vampyromorphs. Ammonites are really common at that locality too so by rights we should have found such fossils. So why haven't we, I wonder? Maybe they were particularly gelatinous or had a peculiar chemical make-up that just wouldn't preserve.
One day one of those academics will find one. Then again, it might be you, Kevin, Spartacus or any of us. I think that's part of the fun of palaeontology, anyone can find something really exciting!
My Polish runner, Martin knew nothing about fossils until I showed him my humble assortment & what is lying about around here, when I told him how old they were he flipped hence he's finding out about fossils at home but at temperatures down to -30 deg.C winter digging is limited to doing it indoors ! Vodka stops their blood freezing I'm reliably informed.
As for who finds soft ammonite body parts 1st - race ya !
I'm still due a bit of marine reptile, perleaze !