Okay, this is an incredibly long story made short. Nicole got a momma gerbil and her 4 mostly-grown babies for her birthday. The bottom picture is of Nicole holding one of the "teenagers." When Nicole came home from school today, she went to check on her gerbils, and lo and behold!! MOM HAD GIVEN BIRTH AGAIN. Yeah, we were shocked.
As it turns out, gerbils mate again immediately after giving birth, and then have another litter about 6 weeks later, which is how old the "teenagers" are.
I'm telling you, you learn something new every single day. :)
And don't worry: the buck stops here. There was no daddy around here to mate with this time. Whew!!