Clever design.

I’m not a fan of stitching into the back bump of a chain but the tentacles are done with the bigger hook, so they’re easy to execute.

Safety issue:
The eyes are inserted on the mantle, whose underside is exposed.
The back stem of the two part animal eye sticks out under the mantle. The eye doesn’t go into the stuffed part.
Solution
To prevent the stem from causing a problem, after inserting the eye in place, trim the stem close to the backing piece.
Make a magic ring of 6 stitches with the project yarn and a smaller hook (C, D or E). Join and leave a tail.
Attach the circle to the mantle back, over the eye area with invisible stitches.