Frag plugs, also known as reef plugs or coral pins are an excellent substrate that every marine aquarist should have at home. The artificial rocks mostly have a hole in the middle, in which SPS can be optimally placed. Use coral glue to fix the frags. Fill the hole with the glue, place the tab and let the coral glue harden.
The stones usually have different shapes, so that you should always find suitable stones for the corresponding frags. The clam holder is ideal for Tridacna clams, which attach to this by the bysutic threads. So the clam can be moved in the aquarium if necessary.