It could be the Naval-launched Brimstone Sea Spear that is a maritime variant for use against swarms of small boats named Sea Spear.
The Brimstone is an air-launched ground attack missile developed by MBDA for the Royal Air Force. It was originally intended for “fire-and-forget” use against mass formations of enemy armor, using a millimetric wave (mmW) active radar homing seeker to ensure accuracy even against moving targets.
Maritime Brimstone provides a unique and unrivaled all-weather, rapid anti-swarming FIAC capability weapon, offering the naval operator the option of engaging a wide range of target types, including fast-moving individual targets in cluttered environments, in both direct and indirect fire modes.
Maritime Brimstone is the latest member of the proven Brimstone Weapon System family; building upon the successful deployment of Brimstone into front-line operations with the RAF.