Question on 603 expansion tank

[C Sean Watts]

I just got my replacement tank from fastlane (old one cracked - 20 yr old plastic) and there seems to be a small white block in one of the chambers. I am familiar with chemistry and I was wondering if anyone knows if this is an electrolysis block IE: sacrificial zinc, etc. Having seen how these can save an ocean going boat and its engine, I like the idea.