Bird's Nest (Seriatopora)
A variant of Pocillopora (cauliflower coral) (Pocillopora damicornis)

Photo: (c) Bernard DUPONT, some rights reserved (CC BY) · CC BY
A closely related Pocilloporid with much finer, needle-thin branches sold alongside Pocillopora under the 'bird's nest' name in pink, green and neon.
Other SPS Corals variants
Pink / Purple PocilloporaGreen PocilloporaWWC Rainbow PocilloporaWWC Fallout PocilloporaORA Green DamicornisORA Pink DamicornisORA Pink & Green DamicornisNeon Green PocilloporaVivid's Toxic PocilloporaPurple PocilloporaGreen Tip Purple PocilloporaPink Cauliflower PocilloporaPink Peony PocilloporaCadmium Pocillopora