Tentoroid

Tentoroid (テントロイド) is the name of three hovering ladybug enemies in Mega Man X4 that appears in Split Mushroom's stage, Bio Laboratory. The name Tentoroid comes from tentoumushi, which means ladybug in Japanese. 

Tentoroid (sub-boss)
Tentoroid is the sub-boss of Split Mushroom's stage, a strong purple Tentoroid that hovers in the lower part of the screen, between thorns and the floor, and make spikes appear from its back to crush the floor panels above it. He is easily damaged by charged shots, however, time is limited as he destroys the floors X or Zero stand on. Once all of the floor tiles are destroyed, they will fall on to the spikes below and be killed instantly. Optionally, X can use Frost Walrus' Frost Tower weapon and lay it above the tile he is about to destroy, then move out of the way. It will only take three or four Frost Towers to destroy him. The Ground Hunter and Aiming Laser also work, whereas with Aiming Laser, X doen't have to wait for the Tentoroid to destroy the tile.

As Zero, Raijingeki (from Web Spider) or Hyouretsuzan (from Frost Walrus) work exceptionally well. The Hyouretsuzan can actually penetrate the tiles' thickness and hit Tentoroid while it is still roving on the spikes. If Tentaroid breaks one of the higher-up tiles, Zero can also use Ryuenjin (from Magma Dragoon) to deal massive damage. 

Tentoroid BS
Tentoroid BS is an indestructible Tentoroid that spins fast to crush enemies with its spikes. BS could stand for "Black Shell". 

Tentoroid RS
Tentoroid RS is a red Tentoroid that hovers slowly through the stage.