Virgularia mirabilis lives in fine sediments (muddy sand to soft mud). The species is found in sheltered inshore waters, or in deeper water offshore, from 12 - 400 m depth. The species is often very abundant in sea lochs or man-made harbours.

Virgularia mirabilis is a sea pen of up to 60 cm tall. Its leaf-like tiny branches tappering at the bottom and the top of the colony give it a delicate feather-shape. Generally, the internal calcareous axis is visible at the upper end of the sea pen. Embedded in mud, the long stalk reaches the half of the whole length of the colony.