Lol!
Tentacle is the fifth stage in Gradius. The theme song is Mazed Music, which was remixed for the Big Core MK I in Otomedius G.
This level consists of Tentacle Golems, odd things with arms that rapid fire at the Vic Viper. The arms can be destroyed by shooting the discolored segment on their arms, to which the Tentacle Golem will simply float away. The core itself can be destroyed, but it takes many hits before they explode, so it's often best to just destroy the arms, and let the Tentacle Golems float away. At the end, you face a rush of many armed Tentacle Golems, followed by the Big Core for the final time.