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