From the Super Mario Wiki
An Astro-Lanceur is an enemy appearing in Super Mario Odyssey. Only six appear in the game, specifically within the Moon Kingdom. They resemble Mollusque-Lanceur (fought in the Seaside Kingdom). These enemies are large, flying, silver octopus-like creatures with six arms. They have four spikes protruding from each arm as well. Touching one of these arms will deal one point of damage. They spit cone shell projectiles at Mario as an attack. These shells explode upon contact. The top of their heads bear the outline of a light blue Ground Pound symbol; Mario can defeat this enemy with a Ground Pound to said spot; doing so will defeat the enemy and release eight coins. These enemies are generally harmless while in the main hub of the Moon Kingdom but can become a nuisance in the platform challenge sections that require Mario to long jump while under the influence of low gravity where it is easy to hit one of them due to their large size.