This small brown thing appears every night in my tank. I always see it floating at the surface of the tank and it seems to stay in place at the current. I would’ve thought they were just waste but they stick in the same place and disappear by morning. There used to be 2 of these but one of them disappeared yesterday. They look like eggs of some kind but there’s nothing in my tank that would’ve laid it and they’ve been there for about a week now. All I have in my tank is a clownfish, a royal gramma, a yellow watchman goby, scarlet cleaner shrimp, strawberry conch, 2 nassarius snails, porcelain crab, and a bubble tip anemone. I have some other things like some soft corals as well.