Pentaceraster mammillatus is a sea star from the Oreasteridae family. It has long, thick arms with triangular cross sections. There are white rounded projections all over the body, in the form of knobs. Hence, it is also called Knobbed Sea Star.
This species is present across the Indian Ocean. It is found on soft substratum, coral reefs and in sea grass meadows. Its diet consists of small organisms and dead matter.
The conservation status of this species has not been evaluated.
 ‘Pentaceraster Mammillatus’.
The arms can reach a diameter of 15cm.