Type locality of Stigmatopora harastii, New South Wales, Botany Bay, Kamay Botany Bay National Park, Kurnell, scuba dive area 'The Steps'. Known from three areas of New South Wales: Botany Bay, Shellharbour, and Jervis Bay. Single individuals or male-female pairs of this species were observed to be closely associated with the red algae (appearing to be of the family Gracilariaceae and possibly of the species Crassiphycus secundatus), which were attached to flat rocky substrate that was usually covered in sand. However, they were infrequently detected and present in only one isolated clump of red algae among all the other clumps in the close vicinity. Most times individuals were absent or only a single individual was found, probably suggesting fluctuations in the abundance of the red algae with which this species associates with. Individuals found oriented vertically or at an angle, were extremely well-camouflaged within the red algae, the distal third of their tails clasped around single fronds. The habitat subject to strong surge, have individuals of this species and the red algae swaying together in unison with the surge (https://vimeo.com/229093467). It has also been observed on occasion where active individuals swimming from one clump of red algae to another or feeding actively just outside the red algae. Feeding behaviour appears to be similar to other congeners, with individuals darting out from the cover of their alga to capture food such as small copepods and shrimp. Individuals have been also observed nearby between the Steps and the dive site locally referred to as the Leap, one of which was associated with another species of red algae appearing to be of the genus Gracilaria. Similarly, a female individual in The Gutter at Bass Point, Shellharbour, NSW at 18 meters depth was observed associating with a clump of bubble red algae appearing to be of a different species of red algae of the genus Gracilaria (Ref. 123272).