The purpose of this comment is to question the organic nature of the material described by Retallack (2011) as 'problematic megafossils' from the Moodlatana and Balcoracana Formations, Lake Frome Group of the Flinders Ranges, South Australia. By way of introduction, we note that there is a considerable history of structures described from sedimentary rocks as fossils that do not stand up to scrutiny (Hofmann 1971, 1992, 2005). The literature is replete with what Hofmann (1992) regarded as dubiofossils. The onus should always be on the author to demonstrate biological origins. Retallack (2011, p.1223) in discussing the need to name problematic fossils states that 'Vendobionta were informally noted by Mawson (1938, p. 259) as 'fossil impressions resembling brachiopod or bivalve form', but formal description of five species by Sprigg (1947) was needed before their global distribution and importance as Ediacaran fossils could be appreciated (Fedonkin et al. 2007).' This is misleading because Mawson's complete sentence is 'Fossil impressions resembling brachiopod or bivalve form, but probably merely impressions of clay galls'. Mawson was in fact describing a section through what would now be termed the Ediacaran Rawnsley Quartzite, from about 1.6 km north of Parachilna Creek and about 50 km to the south east of where Sprigg (1947) initially found the Ediacara biota near Ediacara in the Rawnsley Quartzite.