Shellgeek

Shellgeek (シェルキー) is a virus from the Mega Man Battle Network series. It looks like an oyster. It often hides its shell unless it open up to shoot out needles. It will shoot more than one needle at a time.

Shellgeek
Shellgeek is red and shoot out two needles at a time.

Shellnerd
Shellnerd (シェルニー, "Shellny") is yellow and shoot out three needles at a time.

Shellman
Shellman (シェルジー, "Shellgy") is purple and shoot out four needles at a time.

Battle Chips
Double Needle (ダブルニードル), Triple Needle (トリプルニードル) and Quad Needle (テトラニードル) are the Battle Chips from Shellgeek viruses.

Trivia

 * Shellgeek appears to be based on Shell'n.