Cargo Features

sharks = { version = "0.5.0", default-features = false, features = ["std", "zeroize_memory", "fuzzing"] }
default = std, zeroize_memory

These default features are set whenever sharks is added without default-features = false somewhere in the dependency tree.

std default fuzzing?

Enables std and std_rng of rand

zeroize_memory default = zeroize
fuzzing = arbitrary, std

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

zeroize zeroize_memory
arbitrary fuzzing?

Enables arbitrary ^0.4.7