Skree

Skrees are a type of enemy which have appeared in many games since the original Metroid. They roost from ceilings, quietly rotating their wings around, and dive-bomb other organisms as they pass under, resulting in either their destruction by exploding into shrapnel or escaping by drilling their way underground (by use of their rotating wings); this digging will release shrapnel from the ground.

There are two types: a green variety which appears in the first part of Brinstar, and a blue variety that appeared later in Brinstar after Samus received the Varia Suit. The blue variety is colored as gray in Metroid Zero Mission, but the color is the only inconsistency between the two games. The blue ones are stronger, and have a larger blast radius when they explode. There is a another strain of Skrees encountered only in Super Metroid: the Metaree. This strain is colored light brown and has what appears to be mechanical drills for wings, though it is unknown if this is acquired naturally or artificial through means of enhancements. Skrees also appear in the Metroid Manga, where a pair of them unintentionally save Samus and her group from a pair of Space Pirates by instantly killing them via dive-bomb.

In the Metroid Prime games, the creatures known as Shriekbats (and their many strains) play the same role as the Skrees. The species do not seem to be related, as Samus explains to Kreatz and Mauk that Skrees are one of many predators found "nowhere else in the galaxy."

Metroid
"They stick to the ceiling and lie in wait for Samus. When he approaches, they spin downwards to attack him."

"They use their wings like drills to descend from the ceiling and attack Samus. Be careful of rock splinters when they are digging into the ground."

1986 manga
"When Samus draws near, they will spin and attack. When they burrow into the ground, be careful of the rock fragments."

Official Nintendo Player's Guide
"It attacks from the ceiling screwing down like a drill. If it pierces the ground, it blows itself up."

Super Metroid
"These creatures hang down from ceilings and drop as intruders approach."

Metroid Fusion
Interestingly, despite being one of the Metroid series' signature enemies, the Skree is absent in Metroid Fusion. However, beta trailers show that an X Parasite mimic of the Skree was to appear in Sector 1, but was dropped for unknown reasons. Screenshots show that the sprites were reused from Super Metroid.

Zero Mission
"These creatures hang from the ceiling and drop down to attack when Samus passes underneath. They then self-destruct, inflicting damage with shrapnel from their exoskeletons."

Official website
SPECIMEN ID# G2-003 "Specimen prefers to hang upside-down from ceilings, diving after prey with razor-sharp wings. Interior analysis shows symmetrical pockets of combustible gases, causing creature to explode on impact. DANGER LEVEL: MODERATE."
 * Curved feet and claws
 * Jagged wings
 * Combustible gas pockets (Head)

Trivia

 * One Skree appears in a microgame based on Metroid: Zero Mission.
 * Skrees, in their Metroid: Other M appearance, no longer burrow themselves into the ground in an attempt to damage Samus; rather, they swoop back to the ceiling and attempt to drop onto Samus until she kills them.