Morchellium argus, the red-flake ascidian, is a species of colonial sea squirt, a tunicate in the family Polyclinidae.

It is native to shallow water in the northeastern Atlantic Ocean, especially round the coasts of Britain.

It is found at depths down to about 10 m (33 ft) mainly in caves, under overhangs and on vertical surfaces, often among foliose algae.

The early developmental stages take place inside the zooid and the larvae are later liberated into the sea.

After a short free-living stage, these attach themselves to a surface, undergo metamorphosis, and start a new colony.