Warrior with Ironbark Protector?

[Kerkermeister 1]

I just faced a C'Thun Warrior with my Priest in a standard ranked match. Near the end he dropped an Ironbark Protector after playing Golden Monkey. I did manage to win, but I'm wondering how he could have gotten this Druid basic card.

Unfortunately I have not recorded the game, but here I'll attach a hard copy of the HDT replay.

So at the top he played Golden Monkey, which should have turned his only three cards in hand into Legendaries as he was already fatiguing. But without any fancy stuff going on in between, he played Ironbark Protector two turns later.

Any ideas how he could have gotten this card?

[positiv2 953]

The only thing that comes to my mind now is Shifter Zerus. It could have transformed into Ironbark Protector.

[Kerkermeister 1]

Thank you, that explains it perfectly as Shifter Zerus can transform into any minion!