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