StarCraft 2: Heart of the Swarm Zerg unit teased

As promised, Blizzard have released another silhouette for a new StarCraft 2 unit to be added with Heart of the Swarm. The last one was some sort of OP Terran shape . This time it's a Zerg unit, but WHAT IS IT?

Facebook commenters are torn. "infested stalker," says one. "It's obviously a flyer," says another. "Its kind a like extra-armored evolved roach. Whatever that is," says another. We turned to resident StarCraft 2 nerd, Rich for DEFINITIVE ANSWERS.

"A weird Ultralisk or a Lurker," he said. See the full image below and decide for yourself.