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