The Blastula are a species from an unknown planet that conquers other planets with the intention to strip them of their resources. The Blastula increase the temperature of planets they conquer to make themselves at home.
They appeared in "The I Married an Alien Syndrome". The MIB organization discovered a large spherical ship at the edge of the galaxy belonging to the Blastula with the intention of stripping the Earth of all its resources just like many planets before. They must first make the planet's conditions suitable to their species and must increase the surface temperature enough that it becomes intolerable to humans but comfortable to them. However, MIB infiltrates the group and their actions are stopped by Kay and a Blastula scout who found "Paradise" on Earth. They destroy their sun spot-creating machine and return the planet to a much cooler temperature. They return in "The Quick Clone Syndrome" with other plans to take Earth but are defeated by Kay and Jay.