Measure Oysters Calendar Schedule	April: Thursday evening and Friday Afternoon Class: Post -Metamorphic Seed Culture. Just like the caterpillar that changes into the butterfly, shellfish larvae undergo metamorphosis and change into their smallest juvenile Spat. This is usually the last place they will live, give or take a few meters, for the rest of their lives, unless they are cultured. Our shellfish are just getting ready to move all over.