My phone camera’s macro mode on the ultrawide lens genuinely came in handy today! I was debating with my six year old that this was probably not officially called a “studless holey beam” even if they called it that at LEGO camp.
According to the part number, it’s officially a Technic liftarm. The Internet seems to agree it is also referred to as a beam! And I’ll allow the “holey” part, I suppose…
https://www.bricklink.com/v2/catalog/catalogitem.page?P=32316
Macro photo of the same mystery part with the tiny copyright notice and part number 32316 visible
Photo of a mystery LEGO piece, the part number unreadably small
