In the area beside The Watermill, there is a tree with a small low-poly representation of a Japanese Rhinoceros Beetle attached to it. This pairs well with a bit of cut content recently found within the game's code for the same area, where Ico could have gained a secret weapon that took the form of an Insect Net.

How these two elements could have come together remains unknown, but it was likely part of a reference to Ico's voice actor, Kazuhiro Shindō, and his prior role as 'Boku' in the first installment of the Boku no Natsuyasumi series.

Boku no Natsuyasumi had an extensive bug-catching and beetle fighting system. These features reappearing in ICO were potentially meant to be an elaborate reference, playing on the idea that Kazuhiro Shindō is once again voicing a young boy, who might refer to himself with the first-person pronoun 'boku', if he were to speak Japanese.