I've had these models for over 15 years. They were bought at a games show in Plymouth, and I just never got around to painting them. I was rummaging in my old tool/paint box the other day and came across them, and thought they'd make ideal 15mm monstrous aliens.
They are small Citadel Miniatures Tyranids, which later became known as hunter-killers, then as termagants. They show the characteristic early Tyranid shape: large head with 2 main eyes, plus an additional pair of eyes on small stalks partway along the head, and the holes in the neck are the ear canals. They follow the usual centauroid Tyranid pattern (as seen in Zoats and Genestealers), with a pair of arms, followed by webbed claws (aids moving around in the microgravity environment of a hive ship), with hooves at the rear.
The figures had their slottabase tabs snipped off and were araldited (epoxy resin) onto 1p pieces. To add a little variety, the second one had the tail curved upwards and the rear hoof lifted into a running pose.
After a grey primer spray undercoat, they had a base coat of GW/Citadel "Rotting Flesh". The weapon hoses are GW "Worm Purple", and the guns are GW "Woodland Green". The backpacks are Humbrol matt 29 dark earth. The whole model was given a wash of watered down Humbrol 33 matt black, with undiluted black painted into the deepest shadows. Highlighting generally involved a drybrush of the base colours, followed by lighter drybrushing with a little white added. Teeth were finished off with GW "Mithril Silver".