Prime numbers are common in plants but not so common with animals unless you are talking about starfish.

The eleven-armed sea star, Coscinasterias muricata, is our largest starfish and very common here in South Australia.

There were plenty of these starfish under Edithburgh Jetty but this guy was the only one nicely posing for a photograph.

Photo: Robert Rath, ‘Primes’ 1/200s f/5.6 ISO320 15mm