I love south lido and in the past 4 years that i have been living in sarasota i have been frequently visiting south lido. I love the nature walks as well as the beach and the hidden mangroves in and at the end of the beach itself where it breaks up into small tunnels. We found the outer shell of a sea urchin on the walk itself. I have actually grown up in an area of the indian ocean where there are thousands of urchins along the ocean floor.
Urchin’s roam the floors of the ocean, and although painful if stepped on, they are the preffered food for multiple animals and fish as well as a delacassy in many parts of the world including the greek islands. I would guess that the shell we came across was broken by a predator. Sea urchins have interesting anatomy as there outer body is known as an aboral surface. The spines help protect it from predators trying to break through to the meat inside. the base that they constantly rest on is their mouth where they feed off bacteria on the ocean floor.
When they die their shells harden to these beautiful calcified shells that show where the spines once were. On the beach i collected one and as you can see in the picture the center is missing which is where their soft spot is.