It is a Macrodactylis doreensis anemone, or long tentacled anemone. This one looks a tad bleached. They require mature systems, stable, good water parameters and good lighting and they need deep enough sand beds to burrow their foot into. Don't really host any clown fishes, I think skunk clowns like to host them.
Only a very little bit. If tentacles still sticky its a good sign. Do not force feed it. Do not push it into its mouth. Just a very small piece. Can even try flakes.Feed the nennie some hake pieces, and if you can get some fish roe, they love it as well as sea urchin meat....
depends on the age of the globes, age of the specimen, depth of the specimen within the tank and a few other parameters.