What sea creature can have an eye measuring 16 inches across

Giant squid

Explanation:

Squids are a type of animal that belongs to the Architeuthidae family. They have the ability to grow tremendously and thus become deep-see gigantism. They are deep ocean-dwelling organisms and are widespread and are present in most of the oceans of the world. Their body is dived as mantle, arms, and tentacles. Arms and tentacles are responsible for the length of the squid and play an important role in food capturing and some other process.