oh, life is badass and is doing this all the time. The opposite (nobody evolves to survive) will be very improbable.
In a similar past scenery all known species of Ammonitoidea vanished and dissapear, but some similar cephalopods just lose the external shell, growth a skin over the shell somehow or put the remains of the shell inside the body and its descendants are doing fine as octopus, squids and cuttlefish.
It will be a disaster for the humans that need clams, crustaceans and sea ursins to feed this families, and hundreds of marine species will not survive of course, but for a few species this will be a real blessing.
What makes you confident of that?