Missing Spawning Pool?!

I’m new to the game (started 2 months ago) but I’m pretty sure that Zergs would always require a spawning pool in order to make army units. Though, yesterday I found myself in a game where my opponent was still able to make units (zerglings, corruptors…) even after I had taken down is spawning pool.

I watched the replay afterwards, and indeed I couldn’t see any spawning pool anywhere on the map, and the Structure view/summary at the top left corner would also confirm he/she didn’t have a spawning pool when making those new units.

Is there some aspects of the mechanics I have misunderstood? Is not the case that a spawning pool would always be required? If not, please explain when it’s not the case.

Or if it is indeed required, please let me know what’s the best way for me to share a screenshot and the replay for people to comment.

Spawning Pool is only required to make Zerglings and Queens, and construct Evolution Chamber, Roach Warren, Baneling Nest, Spine Crawler and Spore Crawler.

Any other units that has their own required structures to be produced such as Hydralisks or Corruptors can be morphed even is you are missing Spawning Pool.

For the Zerglings, did the person actually initiate the Zergling morphing after the Spawning Pool was destroyed or before? If you have started to produce something you can still complete the units queued.

I am abit uncertain but I think you can queue five Battlecruisers from an Starport and still have all be produced even if the Fusion Core is destroyed.