Question

. I am an ocean animal and also one of the oldest living
animals on Earth. My body is almost entirely made of
water. Sometimes when I wash up on the shore,
I become invisible. I am a
I am a sea animal, and I can grow up to 18 metres in
length and can weigh up to 275 kg. I have the largest
eyes in the world. My eyes can be as big as a basketba
I am​

Answer 1

I think your answer is jellyfish.

If it's not, then it may be squid.