diff --git a/src/core/src/collection.rs b/src/core/src/collection.rs
index 8cc6129cf4..9f708381ef 100644
--- a/src/core/src/collection.rs
+++ b/src/core/src/collection.rs
@@ -6,8 +6,7 @@ use camino::Utf8PathBuf as PathBuf;
 use crate::encodings::Idx;
 use crate::manifest::{Manifest, Record};
 use crate::prelude::*;
-use crate::signature::Signature;
-use crate::storage::{FSStorage, InnerStorage, MemStorage, SigStore, Storage, ZipStorage};
+use crate::storage::{FSStorage, InnerStorage, MemStorage, SigStore, ZipStorage};
 use crate::{Error, Result};
 
 #[cfg(feature = "parallel")]
diff --git a/src/core/src/encodings.rs b/src/core/src/encodings.rs
index ac69cd58eb..f8934596dc 100644
--- a/src/core/src/encodings.rs
+++ b/src/core/src/encodings.rs
@@ -1,8 +1,6 @@
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
-use std::convert::TryFrom;
 use std::hash::{BuildHasher, BuildHasherDefault, Hash, Hasher};
-use std::iter::Iterator;
 use std::str;
 
 use nohash_hasher::BuildNoHashHasher;
diff --git a/src/core/src/manifest.rs b/src/core/src/manifest.rs
index c82ca6ee1e..7441a9b69f 100644
--- a/src/core/src/manifest.rs
+++ b/src/core/src/manifest.rs
@@ -1,4 +1,3 @@
-use std::convert::TryInto;
 use std::fs::File;
 use std::io::{BufRead, BufReader, Read, Write};
 use std::ops::Deref;
@@ -12,7 +11,7 @@ use serde::{Deserialize, Serialize};
 
 use crate::encodings::HashFunctions;
 use crate::prelude::*;
-use crate::signature::{Signature, SigsTrait};
+use crate::signature::SigsTrait;
 use crate::sketch::Sketch;
 use crate::Result;
 
diff --git a/src/core/src/signature.rs b/src/core/src/signature.rs
index da38587dc3..0ab8190f98 100644
--- a/src/core/src/signature.rs
+++ b/src/core/src/signature.rs
@@ -6,7 +6,6 @@ use core::iter::FusedIterator;
 
 use std::fs::File;
 use std::io;
-use std::iter::Iterator;
 use std::path::Path;
 use std::str;
 
@@ -18,7 +17,6 @@ use typed_builder::TypedBuilder;
 
 use crate::encodings::{aa_to_dayhoff, aa_to_hp, revcomp, to_aa, HashFunctions, VALID};
 use crate::prelude::*;
-use crate::selection::{Select, Selection};
 use crate::sketch::minhash::KmerMinHash;
 use crate::sketch::Sketch;
 use crate::Error;
@@ -891,7 +889,6 @@ impl PartialEq for Signature {
 
 #[cfg(test)]
 mod test {
-    use std::convert::TryInto;
     use std::fs::File;
     use std::io::{BufReader, Read};
     use std::path::PathBuf;
diff --git a/src/core/src/sketch/minhash.rs b/src/core/src/sketch/minhash.rs
index 24cdc9539f..1ee747745a 100644
--- a/src/core/src/sketch/minhash.rs
+++ b/src/core/src/sketch/minhash.rs
@@ -2,7 +2,7 @@ use std::cmp::Ordering;
 use std::collections::{BTreeMap, BTreeSet};
 use std::f64::consts::PI;
 use std::fmt::Write;
-use std::iter::{Iterator, Peekable};
+use std::iter::Peekable;
 use std::str;
 use std::sync::Mutex;
 
@@ -942,56 +942,6 @@ impl<T: Ord, I: Iterator<Item = T>> Iterator for Intersection<T, I> {
     }
 }
 
-struct Union<T, I: Iterator<Item = T>> {
-    iter: Peekable<I>,
-    other: Peekable<I>,
-}
-
-impl<T: Ord, I: Iterator<Item = T>> Iterator for Union<T, I> {
-    type Item = T;
-
-    fn next(&mut self) -> Option<T> {
-        let res = match (self.iter.peek(), self.other.peek()) {
-            (Some(ref left_key), Some(ref right_key)) => left_key.cmp(right_key),
-            (None, Some(_)) => {
-                return self.other.next();
-            }
-            (Some(_), None) => {
-                return self.iter.next();
-            }
-            _ => return None,
-        };
-
-        match res {
-            Ordering::Less => self.iter.next(),
-            Ordering::Greater => self.other.next(),
-            Ordering::Equal => {
-                self.other.next();
-                self.iter.next()
-            }
-        }
-    }
-}
-
-#[cfg(test)]
-mod test {
-    use super::Union;
-
-    #[test]
-    fn test_union() {
-        let v1 = [1u64, 2, 4, 10];
-        let v2 = [1u64, 3, 4, 9];
-
-        let union: Vec<u64> = Union {
-            iter: v1.iter().peekable(),
-            other: v2.iter().peekable(),
-        }
-        .cloned()
-        .collect();
-        assert_eq!(union, [1, 2, 3, 4, 9, 10]);
-    }
-}
-
 //#############
 // A MinHash implementation for low scaled or large cardinalities