Have you ever studied Biology and focused on the topic of evolution? Today's NYT Mini Crossword clue, "Aquatic mammal whose closest terrestrial relative is the hippopotamus," tests your knowledge of marine animals connected with terrestrial animals.

If the NYT Mini Crossword clues are giving you a hard time, our helpful hints and solutions below will help you easily find the answer.

Let's jump in and reveal the answer.

The answer to seven across in the Oct. 1 New York Times Mini Crossword is "WHALE." The clue traces the evolutionary connection between the two species. Despite living in the ocean, whales share characteristics with terrestrial mammals like hippopotamuses. According to the American Museum of Natural History, whales and hippopotamuses both share a common ancestor that lived about 55 million years ago.

There are only a few aquatic animals as large as whales on Earth. When you connect with the hippopotamus, the obvious answer might seem out of reach for many people, as you'd need a working knowledge of biology to know that hippos have a connection to whales through evolution. So, I'd give it a three out of five for difficulty.