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