👉 Ostridae, also known as ostracods or oyster shells, are a group of marine gastropod mollusks that belong to the family Ostracoda. They are characterized by their elongated, shell-like structure, which is composed of a hard, calcareous outer layer called the "shell" and a soft, flexible inner shell known as the "necrosis". The oysters are also known for their ability to regenerate damaged or broken parts.