👉 Synopiidae is a group of cephalopods that includes a wide range of marine animals, including octopuses and squid. They are characterized by their distinctive shell-like body shape, which varies in size from small to large and can be cylindrical or conical. Synopiidae have a number of unique characteristics, such as the presence of a long, thin trident-like structure on the head that is used for sensory and communication purposes.