They were described as mineral sand in nature and if left for one day, they dehydrate to half the size. The "gummy worm" pictured below was perhaps 4cm long and 2.5mm wide with the consistency of a slightly hard gummy worm, but more brittle, like soft cartilage. Canuckenstein noted that one forms every 3-4 days, ranging from 1.5cm to 4cm. She added that the "head" of the worm forms outside his penis.
Forum members identified this as a sperm rod, aka "dried boar glue" (ejaculate).
http://www.guinealynx.info/forums/viewtopic.php?t=68792
Additional search terms: Keywords: white lump / lumpy blob foreskin