Y can't Metroid crawl?

"Y can't Metroid crawl?" is an internet meme that originated on Miiverse. At 10:19am on May 16, 2013, a user named PaulyU asked in a since-deleted post "y cant metroid crawl?" on the Super Metroid community of Miiverse. Attached was a screenshot of the bottom of the second room in old Brinstar, which led to the former Kraid's Lair in Metroid/Metroid: Zero Mission. PaulyU was confused as to how to pass through the narrow gap at the bottom of the room, unaware of using the Morph Ball.

The post quickly went viral on Miiverse, garnering 3,000 "yeahs". It also spread to communities on sites such as NeoGAF and Reddit, with many users mocking PaulyU's obliviousness and the fact that he called Samus Aran "Metroid". Other Miiverse users made similar posts mocking PaulyU's. "y cant metroid crawl?" has since become an in-joke among the Metroid fandom, with some debating whether PaulyU genuinely had trouble beating the game, or was trolling.

Further posts by PaulyU
While the above post is the most famous, PaulyU made several more posts asking how to pass obstacles within the game, including getting through Red Doors, and general navigation.

On May 28, 2013, Kotaku reported that PaulyU had completed Super Metroid with a clear time of 7:35. He posted a screenshot of the baby draining Mother Brain during the final battle against her, captioned with "jellyfish is helping yes". His final post, with a screenshot of his clear time, was captioned "not bad for 1st time and people say old games are short!!"

Acknowledgement by Nintendo
There have been several instances where Nintendo has seemingly acknowledged the meme and made references to it, including in the Metroid: Samus Returns manual.

A Nintendo tweet from April 28th, 2014 promoting NES Remix 2 has an image attached of the Samus and Metroid larva sprites from the original Metroid. It states that Samus "can't crawl" and the Metroid "also can't crawl".

The description of the Varia Suit Trophy in the NTSC version of Super Smash Bros. for Nintendo 3DS ends with: "And, in a feature quite unique to the Metroid series, it lets her [Samus] morph into a ball instead of having to crawl!"

On January 11, 2015, a Zero Suit Samus fighter card was uploaded to the Super Smash Bros. Facebook page. It was captioned "Back in Metroid: Zero Mission. She crawled."

The Metroid: Samus Returns manual's FAQ section includes "y cant metroid crawl" as a question. The answer is "Use [thumbstick down] while crouching to go into the compact Morph Ball form, allowing you to fit through narrow passageways."