What is in this image? Describe it as if you were explaining it to someone from the 15th century.

The illustration before you depicts a fantastical sea creature, subtly akin to a seal, which is a water-dwelling animal commonly found along coastlines. It is depicted as friendly and jolly, resting upon an icy slab in the midst of a watery expanse. The creature is portrayed with smooth, simple lines, giving it a benign and almost jovial appearance. Balanced with its flippers, it playfully interacts with a round object that resembles a small cask or a large nut, hinting at a leisurely nature. This imagery is housed within a stark and flattened perspective, absent of any intricate details one might typically see in nature, thus lending it a whimsical and easily comprehensible appearance. Such illustrations might serve to delight or educate, depicting creatures both real and imagined in a manner that emphasizes their charming characteristics.