Polyps of P. hoplites prey mainly on echinoderms: some types of sea urchin; sea cucumbers (Synapta maculata); asteroids, including the crown-of-thorns sea star (Acanthaster planci); and was observed to feed on nudibranchs as well (Phyllidiella pustulosa was used in a feeding experiment). The corallimorph polyp can attain a maximum diameter of 21cm. Dottyback fish, gobies, wrasses, damsels and cardinalfish have been observed to live unharmed near or among the tentacles of this corallimorph. It also plays host to commensal shrimp (Periclimenes holthuisi, Periclimenes lacerate, Stenopus hispidus and Thor amboinensis).
Found at depths of 1 to 28m, although majority have been observed to live in water of less than 10m. They prefer to settle under coral ledges and in reef crevices.
Spotted this mid-sized corallimorph in about 12m of water at the Coral Gardens dive site, western coast of Talikud Island, Davao Gulf, Philippines.