It is native to shallow waters around Australia and in the South China Sea where it lives in a cavity it creates among seagrass roots and in empty oyster shells.

The body of this peanut worm is divided into an unsegmented, bulbous trunk and a narrower, anterior section, called the "introvert".

When the worm is contracted, the body wall is slippery, possibly lubricated by secretions from glandular cells in the dermis and epidermis.

[3] Themiste cymodoceae is native to Australia where it inhabits the subtidal zone[3] as well as the South China Sea.

The worm gradually excavates a chamber with compacted walls in which it lives permanently, protruding its introvert to feed.