I realize it's NTFS and eject it, then plug it into the Toshiba to re-format it. What-a-ya-know, Mac has wiped THE ENTIRE FLIPPIN, CAKE TAKIN', GOAT-BALL EATING HARD DRIVE - WITHOUT EVEN ASKING ME! Great job tech companies. Way to work together.
So, now I wait another ~15/30 minutes while I try to recover the data/partitions. Otherwise I'm back to square 1.