button polyps
here is what i found on swf on them
<strong> posted on the site:https://www.saltwaterfish.com/c_button.html
The Button Polyps, upon first glance, look like they would be very easy to care for and luckily this is true! These corals are very hardy and usually relatively inexpensive.
The little round button-like polyps cover a rubbery mat, which either interconnects or separates each polyp. Their characteristics are a bump or mouth in the center of a round polyp with tiny tentacles evenly spaced in a circle. They have small stalks and like the Star Polyps, they also resemble tiny underwater flowers bunched together. Usually they are green and blue while another popular Button Polyp are the Yellow Button Polyps.
Button Polyps also contain zooxanthellae, which make it unnecessary to feed them if they are supplied with excellent water conditions and moderate lighting. The Button Polyps will eat brine shrimp and other food solutions but it is not a necessity. A moderate current and moderate lighting is all that is required to keep the Button Polyps happy.
With an Iodine and Calcium solution, in addition to regular water changes, the Button Polyps will grow and multiply at a moderate speed. Their tiny tentacles are used to capture food and will not interfere with other corals in the tank. Be sure to keep these specimens away from hard corals, (Bubble, Elegant, Hammer) which possess sweeping tentacles.
Like the Star Polyps, if the Button Polyps are placed next to neighboring rocks they will easily grow onto them. These newly covered rocks may also be moved to other parts of the tank.
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here are some pics on that site