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