Here are a few additional points:
* тюлень is the general term for a seal.
* There are other specific names for different types of seals, such as морской лев (морской = "sea", лев = "lion") for sea lion, морж (pronounced "morsch") for walrus, etc.
* You can also use печа́ть (pronounced "pechat") for a seal as in the sense of a stamp, like a "seal of approval."
Let me know if you have any other questions! 😊