Milk Gun

Description
"Squirts milk on aliens, causing an allergic reaction. Effective against unprotected aliens." The damage is only 1/4 if it's against the aqualung and snorkeled aliens. Upgrading this building into Level 5 allows you to deploy a Level 2 Milk-Gun with only cost a Level 1 Milk-Gun in battle (10 Milk).

Level upgrades
Without the Lab researches, the Milk Gun has the following attributes:

Switching to another towers
We can switch Milk Gun to Gatling Gun (or to CowBoy).