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