Rust community members are known Rustaceans which is a play on the word crustacean. Crabs are a well-known crustacean. Crab in a human skull is a visual metaphor for learning Rust.

I got a Hamlet vibe from it when I picked the book up when it originally released. It could just be because it looks pretty sick though

Alas, poor Yorick; I knew him well, Ferris.

(Slightly more seriously, the project to replace the borrow checker was called Polonius[1], so it wouldn't be the first Hamlet reference in Rust land.)

[1] https://github.com/rust-lang/polonius

To follow up that movie reference with the response in a different movie where that line is misquoted, “Where’d you hear that, a renaissance festival?”

I haven’t seen that movie a lot, but that scene (and really the entire movie) has been seared into my consciousness for 30 years. It was just the exact thing I wanted at that point in my life.

I do not know the story, but I remembered the book because of that, and now after having mentioned it here, I just bought it.

So my n=1 study indicates it was a successful design. :)

Author here!

To be fair, there is no particular backstory. I picked a hermit crab as the book logo since crabs are strongly associated with Rust due to Ferris, Rust's mascot. I then landed on that style (and the skull) because they looked sick and distinctive. The cover images of many technical books are incredibly dull these days.

IMO thats a better reason than "long winded explanation of symbolism" :D