Two times per week, Jeopardy! GOAT Ken Jennings runs 'Kennections,' a quiz featuring seemingly unrelated clues where the answers have one thing in common. To celebrate his 400th Kennection, Jennings scoured the archives and selected 15 of his most challenging quizzes yet. See if you can figure them out.

1. A common denominator

See if you can figure out how ultraviolet-light seeing animals and chess pieces are similar

2. A few degrees of separation

The word for a group of crows and a 5th-century German tribe have one surprising link.

3. Not exactly polar opposites

Adam Sandler and an African island nation share an unexpected trait. 

4. A humerus connection

St. Paul and the Latin name for the city of Troy have more in common than you might think. 

5. A common thread

Stitch together the clues to see how the shape of Hermione Granger’s Time-Turner and an Owl City single are related

6. A tough sell

Aladdin’s magical object and poison-secreting creatures are the stars of this puzzle

7. More than just horse play

Follow the trail to see how a daily newspaper and a Catholic feast are linked.

8. A comedic connection

Deduce the link between a 1959 musical about a striptease legend and a minor prophet. 

9. A puzzle for a wordsmith

See if you can figure out how bridge is related to Richard Nixon. 

10. A proper difference

Frederic Chopin’s native language and a bustling Moroccan port city famed for its delicious oranges share a trait. 

11. An out-of-this-world theme

General George Custer’s middle name and a 1945 Benjamin Britten guide are clues to this astronomical answer. 

12. Sounds like a geographic challenge

A 1989 hit song by The B-52's and the name of Philadelphia’s arena football team will lead you to the correct answer

13. A lyrical link

See if you can figure out how the name B.B. King gave his black Gibson guitars and a beloved Disney Cocker Spaniel are related

14. An elite enigma

Find the link between the island Odysseus desperately wants to reach and the surname of the German royal family that took over the throne of England in 1714. 

15. Common characters

The edible resource you use to power up in Pokemon Go and the leaves often used in Christmas decorations have this in common.