I think I would use something other than felt for the "yellow" part, particularly for a school since felt tends to run when wet and rips easily. Also consider making a small, thin round pillow of another material for the eye as well and then either snap or tack attach it so the whole thing could be washed.
I could use blanket fleece (when I can find it on sale) or maybe flannel...hmm... we're starting an ocean unit (surprise, surprise), so this would be a fun project.
On that note, I have an empty 55 gallon in my classroom and I asked the students what they thought we should put in it (I was thinking they would say lizard or gecko). One little boy asked for firefly squid... he said they were small so that they would fit...
It is nice to see that the ocean (and cephs) are getting the attention of the kids and teachers recognize the interest. When my granddaughter brought in photos of Pot Bellied seahorses while they were studying Australia, the teacher asked her why she brought the pictures to class (shakes head). The media can be such a powerful thing in a good way. It is painful to see channels like Discovery think they need garbage to attract attention.