Last week's answer

Question: In 1980, a massive cargo ship collided with a pier of the original Sunshine Skyway Bridge in Tampa Bay, causing a tragic partial collapse. When engineers designed the iconic new cable-stayed replacement bridge that opened in 1987, they pioneered a massive, heavy-civil defense system surrounding the new main piers. What structural safety feature was added to prevent ships from ever striking the bridge columns again?

Answer: A series of massive, rock-filled concrete islands called "dolphins" built in the water upstream and downstream of the piers to safely ground out-of-control ships before they reach the structure.

Dolphins effectively work as bumpers of boats and were placed along the main span of the bridge to protect all of the main supports. They stick down to the bottom of the channel and rise about 15 feet above the waterline. They are 65 feet across. There are 36 of them placed around the bridge. 

Sources: WUSF