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