What is pen of squid?

Squid have a specialized organ called a pen, which is a long, flat, and durable structure made of chitin, a tough material found in the exoskeletons of arthropods. The pen provides support and structure to the squid's body, keeping it streamlined and stable in the water. The shape and size of the pen can vary depending on the species of squid, with some being long and narrow, and others being shorter and wider. The pen can also be used for defensive purposes, as some species are able to eject it from their body in order to distract predators and escape. The pen is an important anatomical feature that has helped squid to survive and thrive in their marine environments.