The most common and most likely answer to this crossword clue is the 5 letter word UBOAT which also is the latest solution we found used in New York Times in 1959.
Nautilus' ancestor crossword clue answers
Here's a list of possible crossword answers ranked by the most likely to least likely.
| Answer | Likelyness | Letters | 
|---|---|---|
| UBOAT | 100 % | 5 | 
Words with a meaning similar to the clue: Nautilus' ancestor
These words may or may not be a possible solution to this crosswords clue.- omen
 - sub
 - active
 - acton
 - advance
 - bend
 - can
 - cans
 - captain
 - center
 - cna
 - color
 
Crossword Answer definitions
More crossword clues leading to the same solutions
Here's a few more crossword clues - all leading to the identical solution