The short population census conducted at Cyrene Reef on 8 and 9 May 2008 revealed that there are at least 62 individual knobbly seastars (Protoreaster nodosus) at the intertidal habitat. This is perhaps the largest Protoreaster population ever documented in Singapore. The population size is likely to be much larger than estimated as the two surveys were carried out on only a small (~20% of total area) intertidal area of Cyrene Reef. In addition, the population contained a wide range of body size (minor radius: 21-56 mm). There were at least 12 juveniles, which are seastars with minor radius less than 30 mm. The presence of juveniles, subadults and adults indicated that there is a healthy level of recruitment at Cyrene Reef. This habitat may be the only sustainable population of knobbly seastars left in Singapore today.