Does a face-down creature turned face up count as entering the battlefield for enter the battlefield triggers?

When a creature is first played face-down via Morph or a similar ability, it enters the battlefield as a 2/2 colorless, nameless creature. That entry is when any enter-the-battlefield (ETB) triggers would check — not when it is later turned face up. CR 702.37e confirms that turning a permanent face up is a special action that changes its status, not a new event of entering the battlefield.

CR 603.2 specifies that ETB triggered abilities trigger when a permanent 'enters the battlefield.' Turning a face-down permanent face up does not move it from one zone to another; it stays on the battlefield the whole time. Because the permanent never leaves and re-enters the battlefield, no ETB trigger fires at that moment.

However, there is an important nuance: if the face-down creature has an ETB trigger from its true face-up identity, that ability did NOT trigger when it originally entered (because it entered as a generic 2/2, not as its actual card). It also does NOT trigger when turned face up. The ETB window has already passed.

Concrete example: You cast Zoetic Cavern's creature face-down via Morph. It enters as a 2/2. Later you pay its Morph cost and turn it face up. No ETB triggers fire — the creature simply reveals itself and gains its real stats. Any 'when this creature enters the battlefield' ability it might have does not trigger at this point.

Sources: CR 603.2 (ETB trigger definition), CR 702.37e (turning face up is a special action, not an ETB event), CR 400.1 (zone changes are what define entering/leaving the battlefield).