Grainy blood cells
Arthropods are animals with a hard outer shell and legs that bend at joints. Crabs, shrimp, spiders, and insects like caterpillars are all arthropods.
Blood cells float in their blood. Some of these are granulocytes. The name means "grain cells" because they are full of tiny granules, little packets that look like grains of sand under a microscope.
A granulocyte can change shape. It can spread out flat and reach out with soft arms.
Wow!
You have grainy white blood cells too! Some of your germ fighters are also full of granules. Very different animals came up with a similar trick.