Pentamerous
Toothpick
Porcupine
Dome
Algae
Small fish
Other sea urchins
Sea cucumbers
On the beach
Subtidal area only
Both intertidal area and subtidal areas
Intertidal area only
Echinoderms
Strongylocentrotus
Purpuratus
Animalia
Because sea urchins have large numbers of relatively big eggs
Because a sea urchin's egg is relatively big
Because sea urchins have large numbers of eggs
Because the eggs make great omlettes
Mouth
Nose
Feet
Spine