Answer:
A huge sea creature with many tentacles
Explanation:
An appositive phrase can be easy to identify in the middle of a sentence because when you remove the phrase the entirety of the sentence still makes sense. Just a tip! Also an appositive just adds more information to the noun, in this case the noun is "the giant squid" which we already assume would be a "huge sea creature with many tentacles" therefore that information adds to the noun. Hope this helps!