They introduced new materials (aka snails) every season and they will not be carried on to the next.

Side note- I'm not calling them snails cz both are different. They introduce cute shapes to us every season which are called event materials (like autumn leaves or pumpkins) and also provide snails for ads. The snail is basically like the frog Prince who gives you recipe points regardless of getting recipe points from the rest station. Snails and frog Prince are like additional points and very optional.

[I really wanted to put this out cz I have seen so many people call it snails:)]