Daybeacons

While the number of lighthouses once operational in Texas might seem like a lot there was still much of the Texas Gulf Coast left dark, untouched by the beacons. Building lighthouses at every hazard was a bad idea from a financial viewpoint and wasn't done. So daybeacons marked these spots. A daybeacon is a a simple structure built to warn of danger, it's designed to be easily seen in the day and has no light attached to it. Daybeacons were painted onto lighthouses to increase visibility during the day as well. Below are elevations of daybeacons designed for Galveston.

Pictured below is a daybeacon at Seaflower Reef in Long Island

Image from Library of Congress