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