Anybody know the title of this children’s book?

I wish I could remember more details, but when I was in 3rd grade in the 90s our teacher read a book to us about a crab and his lobster friend that find a lunchbox on the beach with a peanut butter and jelly sandwich in it.

As sparse as those details are, that’s all I remember, other than I liked it. Anybody have any idea what this book could be?