Pentagonal and plump it looks more like a cushion than a starfish. The cushion star has very short arms. They are barely distinguishable from the central disc. Its body is thick and fleshy. It is covered in small spines that give it a velvety texture. The colour ranges from olive-green to brown to orange. Darker mottling is often present. Form follows function. Shape aids concealment. The texture is soft. The appearance is unassuming. Under rocks and in rock pools it hides during low tide. The cushion star is common in the intertidal zone. It must survive twice-daily exposure to air and sun. It wedges itself into damp crevices. It seals its body to retain moisture. When the tide returns it emerges to feed. Survival depends on retention. Exposure leads to desiccation. The cycle is tidal. The response is instinctive. Unlike many sea stars it is not a predator. The cushion star grazes on algae and small encrusting animals. It scrapes food from the rock surface with its tube feet. It moves slowly. Deliberately. It leaves a trail of cleaned rock behind it. It is a browser. Not a hunter. Consumption is gentle. Impact is local. The rock stays clean. The algae grows back. Balance is maintained. Small and well-camouflaged it is easy to overlook. The cushion star blends with the rocks and algae of the intertidal zone. You can stare directly at a rock pool and see nothing but barnacles and seaweed. Only then do you realise that several cushion stars are hiding in plain sight. Their bodies match the background almost perfectly. Visibility is low. Detection is difficult. The eye misses. The creature remains. Intertidal zones provide its preferred habitat. The cushion star lives from the mid-tide mark down to ten metres depth. It occurs on rocky shores in harbours and in estuaries. It is most common in areas with abundant algae. This is the same algae that provide its food. When the algae bloom the cushion stars multiply. Resource availability drives population. Abundance follows supply. The link is direct. Reproduction occurs in spring and summer. The cushion star releases eggs and sperm into the water. Fertilisation occurs there. The larvae drift in the plankton for several weeks. They settle to the bottom. They are tiny at first. Barely visible. But they grow quickly in the warm food-rich waters of the intertidal zone. Growth is rapid. Survival is chance. The next generation arrives. The cycle continues. Climate change may affect its intertidal habitat. Warming waters and rising sea levels will change the distribution of rocky shores. They will change the algae that grow on them. The cushion star is adaptable. But it has limits. For now it remains a common sight in rock pools. A small pentagonal cushion-like presence in the space between tides. Adaptation is tested. Limits are unknown.