That is an ocellaris, but bubble tip, or bulb tentacle anemones, are not their natural host. The natural hosts to ocellaris are H. magnifica, S. gigantea, and S. mertensii. In captivity, they may choose something other than their natural host, if their natural host is not available, like a bubble tip, a coral, or simply a cave in the rocks. It can be hard to predict what a clown will utilize as a host when their natural host is not available.
HTH
Peace
EC