Did this Kombu go bad?

is this Kombu still good? it's quite old, the packaging doesn't have a best before date. I'm mainly worried about it turning brown and when I split it, it doesn't break off completely but I have to twist and turn it. also, if it's still good, my husband briefly threw one into our bio disposal bin (which we empty every day), is it still fine to cook in water and eat?

by funwithpunz