Image: YouTube

This strange creature looks like a rock in all regards — except that it can be sliced open and served up as a table delicacy.

Pyura chilensis is known as a tunicate, endemic to the shallow waters of Chile and Peru. This marine invertebrate animal is a filter feeder that absorbs microorganisms out of sea. It is a member of the phylum Tunicata and serves as an immobile animal enveloped in a hard collection of outer cells that allows it to attach to surfaces.

Its exterior perfectly resembles the visual texture and color of a rock, but its interior is comprised of tissue, blood, and living structures just like any other animal of its class. Pyura chilensis utilizes two tunicin structures for feeding, by inhaling water and filtering out excrement liquid through the other end.

Image: Wikipedia

These rock-like creatures are heavily fished out of Chilean waters and eaten raw or cooked by locals on a wide scale.

One of their most unusual characteristics is the high concentration of the rare element vanadium in their bloodstreams. Research has shown that the concentration of the element in the bodies of tunicates is 10 million times greater than encompassing marine habitats, leading to the theory they are either capable of manipulating the environmental element or producing a mass quantity of their own accord.

The other unique feature of the Pyura chilensis is that although it is born male, it morphs into a hermaphrodite as it ages, resulting in the ability to self-reproduce. The organism can produce both sperm and eggs for procreation, eliminating the necessity for a living partner. 

Check out this video of an actual living rock.