351 rings

Those old beams would have some metal parts to secure the wood, but Leonard Ethan was detecting the middle section of the beams where there wouldn't theoretically be any metal parts.

Realizing that they might have found something extraordinary, Leonard and the others quickly built a makeshift three-layered platform using the boxes and furniture in the attic. Then, the lightest among them, Joan, climbed on top of the pile.

"There's something up there." As soon as she reached the level of the beams, Joan noticed something was amiss and called out, "There are traces of an interlayer on the beams, give me a tool to pry it open."

As seen in the photos taken on the mobile phone, there was a groove dug into the beam, and a palm-sized, rectangular piece of wood covered the groove.

Honestly, this hiding method was incredibly discreet, and since this spot was previously in a human blind spot, it was difficult to locate once the wooden piece was seamlessly covered.