Any chance of booting into Snow leopard?

On a late 2012 iMac running Yosemite; I just got 2 replacements for external hard drives from OWC and am in the process of re-cloning, moving clones, other backups, etc, etc.

I have an old bootable 10.6 clone from a previous iMac and would like to keep it, but the chance of getting any Mac that'll be from that era is very slim, so I'm wondering if I should just ditch that clone or has anyone been able to actually boot off an external 10.6.x plugged into a newer Mac?