I'm hoping that isn't a cross-section of an ant colony in the background.

I think this is a pun.

It's tagged 蟻巣 on Pixiv, which is read as "Arisu" just like Alice's name.
But the two kanji separately mean "ant" and "nest".

The artist didn't add that tag to it, but I think that was the joke he was getting at because the title he gave it mentions a cross-section of Alice.

OOZ662 said:
I'm hoping that isn't a cross-section of an ant colony in the background.

Tough luck.

Oh, Seki.