clarification on 'pendingShares' number and why is it so high

[mboyd1]

the miningcore api reports very large numbers in the billions for pendingShares when querying /pool/[poolid]/miners/[address]

for example for this miner it says there are 42,515,513,500 pending shares.

I am struggling to understand why this number is so high, the asics only submit shares every 15 seconds or something there seems to be no way possible it has submitted 42 billion unique proof-of-work stratum shares. Is this number some multiple of the shares and their difficulty, or is there a decimal place that is way off somehow?

[MiningCryptoLive]

That number is the shares total difficulty