the pink stuff is a sponge, and will probably not do any damage to anything. the item circled in the second picture is an aptasia anemone, i believe. if that is the case, then it should be kilt as soon as possible. get some aptasia control, or joe's juice or aptasia x and follow the directions. and bristle worms are bad for seahorses. get a little 6-line wrasse, but you'll have to get rid of it before you get your horses